Top 10 Modifcations for the 8th Gen 06-11 Honda Civic Si

Overview

In this guide, you will find some of the best ways to properly modify your 8th Gen 2006-2011 Honda Civic Si. We go over the do's and donts and sort through a lot of the products that are out there for your vehicle and help narrow it down so you dont make mistakes along the way.

To start off with this vehicle comes with one of the most popular performance Honda engines of today, The K-Series platform. This platform has been at the fore front of power gains and engine swaps. Currently this is the goto swap into nearly every Honda applicable and for good reason. This specific powerplant in the 8th gen is the K20Z3, very similiar to the K20A, this system utlizes a DBW (Drive By Wire) electronic throttle body to allow the car to operate its VSA (vehicle stability assist), which modulates throttle to help maintain a stable vehicle and keep traction under normal power ranges in check. This is how all new Hondas are the real only limitation is you cant easily run a individual throttle body setup.

The Basics about the Platform

Here we will have a look at each various section of the vehicle, how it performs, what it needs to work better, thoughts and ideas to get yourself up to speed and in the know for the 8th Generation Civic Si. We go over the car, how it performs, where it lacks and give a quick run down, further down below we dive into each part and compare the top brands. Lets begin!

The chassis is solid, but can use some assistance. Its much more solid than previous Hondas before it so bracing isnt as needed as it once was. But you can still go at it with bracing components, as they generally are pretty affordable and easy to install. 

The transmission is decent, with capability of handling 500-600hp. But beyond that you will be looking at building that up with some stronger gears to handle the power. The transmission also comes standard with a gear based LSD. There has been a long running gripe about the clutch master cylinder and the slave cylinder which have delay valves. Which can cause lock-outs and gear grinds in shifts from 1-2nd mainly at high rpm or racing type situations. That can be address by modifying (removing delay valves) or purchasing kits which do not have the valves. As well the vehicle is getting older and most cmc and slave systems fail to work over time or completely loose all hydraulic pressure and a replacement will have to be done. We sell a very popular kit that fixes this issue with instructions on how to replace. You can find that - > 2006-2011 8th Gen Civic Cmc & Slave Upgrade

Handling, from the factory the Si is a pleasure to drive, but the slightly open fenders and possibly a little too soft of a suspension makes for a good choice of just going with a performance orientated coilover suspension which can help dial down the ride height to sit on the tires better and allow you to play with damper settings to really dial in your comfort level as well have some play for track days. We used springs before on the vehicle but found the oem struts didnt like the journey and quickly became worn out and bouncey. Once swapping over to a full coilover kit, it was a pleasure to modify and the suspension lasted. They also include front camber plates and adjustments at the lower shock perch, the rear just needs a rear camber arm. All of these products we have in our suspension section made specifically for the 8th gen civic. 06-11 Civic Suspension

Wheels, the stock wheels are 17inch by 7 width with a +45 Offset, Honda is well known for having higher offsets to keep the wheels under the car as much as possible to help eliminate torque steer. The Mugen Si took it to what is more known as its sweet spot in the handling department by going with an 18inch by 7.5 width and a+42 offset wheel that weighs 16lbs and was built by rays / volk. With proven increases in handling by going to the 18inch, due to less tire squish at higher loads in cornering. It is certainly an upgrade to keep in mind when picking your next wheel for this vehicle. We carry a ton of wheels in those specs, you can find them here in our huge wheel section. Performance Wheels

The ECU & Tuning, as far as this vehicle its pretty forgiving with basic modifications, but if you want to take it further, using a tool like Hondata Flashpro or Ktuner for your vehicle tuning can really unlock its potential. For example the Hybrid Racing Intake is a 3.5inch in diameter, the piping is too large for the MAF to properly read (mass air flow sensor). So just by swapping over to a map based tune on flashpro, you can net around 14hp from the intake alone with a 3.5inch inlet for this car. Which is exceptionally large for a 4cyl, but time and time again its been proven that this K-Series motor likes efficient air. The other part is Rev Hang, Rev hang was something a lot of people just do not enjoy. So Flashpro got rid of it all together and can now even be directly tuned to your exact tastes. Rev hang is quite simply where the revs just hang, versus the more normal quicker drop as soon as you left off the gas or press clutch pedal during a shift. Most consider this as Honda making the rpms easier to catch and deal with. But performance minded people want things to be more responsive and this product addresses that. Also flashpro can be invaluable with datalogs, knock counts, timing and increases all by itself. Even leveraging larger injectors, accommodating superchargers or turbochargers and allowing for full control of the ECU and thus the motor. We have several customers pushing over 500-600-700hp in their vehicles and are running flashpro. Ktuner can do this as well, but it is a newer product and they are always getting better and trading off between each other. Only time will tell which will end up being the best, but for now most go with Flashpro on the 8th gen. But be sure to look into both products and we sell those currently on the site.

The Engine, the engine comes in at 197hp via a DOHC I-VTEC 4 cylinder, with dynos showing the car sometimes nearly putting down what its rated at via the motor, showing Honda a lot of times maybe underestimating their manufacturer power figures. The engines are good for 500-600hp. But at those levels it may go from ok, to not ok pretty fast. Just really depends on the tune and how quick the torque comes in, what sort of turbo or supercharger is being used. Anything above those numbers its time to look into building up the internals and we do carry those items.

Naturally aspirated performance this motor can be improved upon in a large range of standard areas, Intake, Header, Exhaust, RRC (JDM Type-R) Manifold or getting the oem one ported and smoothed. Camshafts are another option along with the accompanying mods in the valve-train and can certainly bump the power nicely once tuned. Even adding E85 to the fuel mixture along with an upgraded fuel system and fuel injectors to handle the increased fuel requirements. Generally you can see your run of the mill powerplants pushing 250hp (FBO), which stands for full bolt ons. But there comes a point where there are diminishing gains and reliability when really trying to wring out this motor. Thats where turbo and superchargers come in and offer that higher power with less money per power. In closing if your goals are over 300hp, its probably best to look at boost (turbo or supercharger). For those who are super interested in a naturally aspirated build, there are some cars pushing 400hp-500hp. Which is nearly jaw dropping, but these types of builds have become pretty famous but are very rare. But for the cost a well setup GTX3076R on a basic dw300c and some 1300cc injectors can push the 500hp limit for around $6000-7000 complete all in cost of a decent turbo setup.

Time to go Turbo or Supercharged? This has become a very popular platform to turbo or supercharger, with a huge plethora of already completed builds basically making an almost guide-book to follow. There are some popular turbo and supercharger setups that can push you from the modest 200hp platform into a 500-600-700hp and beyond monster of VTEC. Generally starting at around 4000+ for the turbo or supercharger setup. We sell a multitude of systems and each one has its own pros and cons. But to make it simple safe and short. These systems have proven themselves to be great power additions. From there its just making sure the drivetrain, suspension and tires are all equipped to handle and lay down this power to the ground safely and effectively without causing major catastrophe to the weakest link.

The shifter, some like it, some hate it. But the good thing, we all have different tastes and there are several options to fill the needs of each buyer. From full metal caged adjustable short shifter kits, to nearly oem plastic and very affordable setups, to even shifter adapters on the low end to get this car to shift quicker and with a shorter more sporty throw. As well there are shift cables to beef up that area, metal bushings and bearings to make a more crisp shifting response. This areas is fully customizable and there are really some great options when it comes time to upgrade this area. To break it down it generally is either the hybrid racing short shifter or the acuity racing short shifter. The newer Acuity short shifter looks to be the new winner from reports from customers swapping over. But the hybrid racing is more affordable and still a long standing quality unit.

Intake, Header & Exhaust, the big three that everyone always has a look at right away when they first embark on modifying the car. The good news is each area provides some solid gains for a 200hp 4cyl car. With the intake netting a possible 14hp, the header 12-15hp and exhaust 7-12hp depending on the brand, piping size, quality and flow and we will be going over all that in this 8th Civic Si Performance guide.

Brakes: The braking system on the car is fine for general driving, spirited driving, even slower speed autocrosses. But if you are looking to hit the real road courses, you are going to need to upgrade the pads to a track based pad. Which are generally going to be pretty hard to use on the street due to the nature of the pads needing to be in a high heat range. We have an Ultimate Brake Kit for the 06-11 8th gen civic Si. This is a great page because you dont have to go searching for the proper part #'s which most manufacturers completely mess up. Another thing is the stock brake lines are squishy, we highly suggest going with a Performance Based 06-11 civic stainless steel brake line that helps make a firm, predictable and reassuring pedal feel from the brake pedal. Also for those who are also just looking for a good stock replacement, we have several listed in our ultimate brake kit guide above and we go into detail all of the products listed and what they do.

The parts (what to get & what not)

1. Intake

When starting out we generally suggest to get an intake. That is of course if your goal is to go naturally aspirate. This mod is perfect if you dont want to spend too much, want a little more performance and enjoy a good running car thats simple. Another thing to keep in mind you can sell off the parts you dont need if naturally aspirated doesnt fit your power goals down the road.

The basics of the intake is pretty simple in our eyes, get a 3.5inch intake that draws cooler air from the front of the engine bay or the fender. Thats it. Your going to net around 14hp with flashpro. So, Which intakes are 3.5inch, thats the only problem. Good news is even though they are limited, we will tell you. Well we have the list right here and we rank them in order.

Top 3 Intakes to get for the 06-11 Civic Si

1st Hybrid Racing Cold Air Intake 06-11 Civic Si
2nd Skunk2 Cold Air Intake 06-11 Civic Si
3rd K-Tuned Cold Air Intake 06-11 Civic Si

These intakes require: Hondata Flashpro and you will set your car to a MAP Tune, which they have in their basemaps.

We will also go over these intakes, how they compare against each other and why we think Hybrid Racing is the best one overall.

1. Hybrid Racing Cold Air Intake 06-11 Civic Si

This intake has the most straight pathed and full featured setup of all the intakes for the 8th Gen Civic Si right now. Its a silicone based intake, with an actual anti-hydrolock feature, this anti-hydrolock prevents you from sucking up water and into the engine which cold air intakes can have occur. The intake is 3.5 inch and its just huge, the filter is huge and this simple but well thought out intake just flat out makes the best power out of all the Intakes on the market for this vehicle. We also believe the construction doesnt absorb engine heat as quickly, so this allows cooler air at all times. Even without it sucking cool air from the fender as is. Add-on the anti-hydrolock, great price, great company and support and you get a winner. Another cool thing is they include a battery tray, which makes you drop the stock battery down lower, which also improves handling but also cleans up the engine bay. This intake also includes an extra coupler for larger throttle bodies. Yet another reason why this is the champ.

2. Skunk2 Cold Air Intake 06-11 Civic Si

This intake is unique in its approach, its a plastic (composite) based intake which draws the cool air from the fender area as well, it also sneaks around the stock battery, rather than dropping it so the intake path isnt as direct. The intake also comes with a smaller maf, so you have to buy a larger one to upgrade to the map tune and grab a tiny bit of extra horsepower, but you can at least run without flashpro, but we still suggest it as the intake does flow a lot more. This intake doesnt have the anti-hydrolock feature, but was built from the compass360 race team and special series skunk2 participated in, which those cars had some serious track time with.

3. K-Tuned Cold Air Intake 06-11 Civic Si

The K-Tuned is an interesting crack at the 3.5 inch intake market, they offer a cold air intake that can convert to a short ram. This is kind of nice since you get the choice of both. However the only drawback and we arent fully sure how big of a drawback this is, but the intake itself is made out of aluminum, which for a long time thats all there really was for intake systems. But this intake does feature a battery tray as well and the piping is decently straight, however hybrid is straighter. This system is also priced a tad bit more than both, so with that all combined even though its great and you cant go wrong, for a lower price and better performance we would just say the hybrid is probably the better choice. If you do however want the short ram when you dont want to risk any sort of rainy season, then here is your winner.