[Former_Boosted_IS]

I have debated installing an exhaust for a long time now, but I just wasn't ready to pull the trigger yet. When I heard HKS had an exhaust for the 335/135 crowd, I was drooling because I know their reputation in the tuner world is second to none. After reading that HKS won the Grassroots Motorsports' dyno shootout on exhausts, I felt the time really had come. I have first had experience with HKS over the years and their products have yet to let me down a single time. The reviews had been superb on the exhaust and after hearing Bimmerworld had a stainless steel tip version, I decided the time had come to order.

Experience with Bimmerworld

Bimmerworld is offering a introductionary price that is very good for a downpipe back exhaust for our car, so I called and spoke to Brian to make the order. Bimmerworld was extremely easy to work with and very professional. I received confirmation the same day and the tracking info was active with hours. I simply couldn't ask for a better experience from a vendor.

Packaging/HKS Exhaust Parts

HKS is obviously on top of things. The box was extraordinarily well packed. Cushions are everywhere, the pipes are all wrapped, and the tips are bubble wrapped to protect them. The box came to my house damaged by the shipper in a few locations, but due to HKS going the distance to package things correct, the parts were unblemmished. Here is the packaging:







Here is a group shot of all the parts. Notice the CNC flanges (no slip joints), perfect welds, fully stainless steel parts, bomb-proof gaskets, etc.



H-pipe next to the stock piping:



Flanges:



Stainless steel canisters:



Resonators and look inside 65mm (2.56 inch) piping:





Welds on H-Pipe:



Stainless steel tips (97 mm/3.8 inch)!!! They even have a brushed look to them!



Instructions and hardware:



Notice the kit comes with bomb-proof gaskets all the way from the downpipe back (nice touch). There will be two sets of bolts... the longer to secure the flanges and the second to mount the rear support plate between the two canisters. Finally you will see a bag with an "I" plug to use on the exhaust, flapper with a cap to keep it looking clean, and a bolt for the stock midpipe hanger with a long thin plastic washer.

As you can see, the parts are nothing less than top notch in every aspect. From the stainless steel polished finish, to the thorough welds, to the perfect canisters, to the resonators... everything is nothing less than perfect. WOW! HKS did this right and thanks to Bimmerworld we have stainless steel tips.


Installation

One of the things I have tried to do on my car is DIY install everything. I wanted to show the DIY guys what to expect. I began by using a fantastic DIY guide for removing the exhaust I found here:

http://www.e90post.com/forums/showth...IY+e92+exhaust

I will cover the parts I feel that this DIY didn't cover, but this is a great start.

I simply used a 3/8" and 1/2" socket to remove all bolts. I did NOT in any way need an impact wrench. I also used ramps to raise the rear of the car and a jack to prop the passenger side to allow more clearance to the downpipe bolts. One thing the DIY forgets is to remind you to remove the flapper rubber tubing. It is on the driver's side behind the bumper and you cannot miss it. Cut it off at the end of the flapper if it gets stuck.

Use the following "I" shaped hardware to plug the flapper and cap it off:



Next you will follow the instructions above in the DIY to remove the exhaust. Remember to leave all rubber hangers left installed on the stock exhaust until you need them so no confusion comes up on where to put them.

Now we will move onto the installation of the new parts.

First, REMEMBER TO LEAVE ALL BOLTS LOOSE UNTIL ALL PARTS ARE INSTALLED. I would suggest starting at the front near the downpipes and moving back. I personally installed the passenger side midpipe first because the top bolt can be difficult where it connects to the downpipe. You will use the bolts from your stock or aftermarket downpipes along with one of the bomb-proof gaskets HKS provides you. If you have a problem propping them up, you can use a jack or really anything to hold them in place. Here is what they will look like when they are installed.



Do not install the center support at this point. Next is the H-Pipe. Remember the rear of the H-Pipe uses rubber hangers, so remove them off the stock exhaust and install them on the new pipe. They should be simple to remove and reinstall with a little elbow grease. Get it lined up under the car and install it using the longer supplied bolts, washers, lock washers, and nuts. Remember the order of the hardware should be:

1. Bolt
2. Washer
3. Flanges
4. Washer
5. Lock Washer
6. Nut

I found getting one bolt in, then installing both hangers was the easiest way to do this. It will look like this when done:





Finally, it is time to move onto each the rear muffler section. Again, you will need the rubber hangers off the stock exhaust, so install them where necessary:



Again, you can use a jack to raise it up into place, or use your leg to rest the exhaust on. Use the supplied gaskets and bolts to secure it and slide the hangers into place. I would do both sides first, then go to the back of the car to slide the hangers into place for perfect alignment.







Now that you have everything installed and lined up, you can start to tighten everything up. START AT THE FRONT CONNECTION BETWEEN THE DOWNPIPES AND MIDPIPES. Now move to the midpipe connection to the H-pipe.



Finally, the rear section mufflers and the H-pipe.



Once everything is tightened, now go back and install the hanger for the midpipes. You will notice the hanger is mounted to the car so it can slide toward the driver's side or passenger's side to work in many applications. Loosen the 50-torx bolts and position it perfectly, then re-install the hanger with the plastic washer and new bolt included in the kit.



Finally, go to the back of the car and re-adjust the rubber hangers to assure your perfect alignment:



Now, it is time to install the flex plate that goes between the two mufflers. Why do you need this? It will assure you perfect alignment as the exhaust heats up and expands. It is forward thinking by HKS and the "HKS" logo is simply gorgeous!!! Use the supplied smaller bolts, washers, lock washers, and buts to install this part.



At this point, really go through to make sure fitment is perfect. I found everything to be nothing less than perfect fitment right out of the box.







In particular, notice the perfect alignment in the exhaust pathway for the stock exhaust.







If you are pleased with everything, finally re-install the “x” brace.

The install is very straight forward and if you could do downpipes, then this should be a piece of cake. An extra hand can help, but I did it alone and really had no problems.

Testing? … Drone?... Power?

HKS has been shown to be the most powerful 335 exhaust on the market and it shows itself on the road. I was concerned that I might not notice a difference, but on the top end the power is noticeable. I think at higher power levels, those stock secondary cats are definitely limiting power at higher horsepower levels. I have no doubt that I was turning higher rpms faster after the install. I will dyno soon to see where I stand. By the way, if you don’t think the stock exhaust is restricting then look at how the exhaust is pancaked in sections!



Power is great, but this is a BMW and should sound sporty with NO drone. That was critical on my selection. The HKS Exhaust is catless but HKS used resonators to get the sound they want and boy did they knock this one out of the park! The sound is very, very smooth and powerful. At idle it is quiet and under throttle it is smooth and throaty. There are no gurgles or drone whatsoever. With the windows up, the car is quiet and light throttle and cruising without a single note of drone. When under throttle the sound is aggressive and just plain mean. It is not obnoxiously loud in any way. Really, the sound is absolutely perfect when mated to AR Design catless downpipes. I am honestly shocked it can sound so smooth and clean with just the HKS resonators.

So, does it smell like rotten eggs? I couldn’t smell a thing inside the car whether driving or sitting still with the windows open. If I stand behind the car, I can smell more, but it is nothing that anyone should really care about to be honest.

Obviously, I can talk all day, but video gets it done. You can find many videos of the exhaust revving but I wanted to focus on the sound in the cabin with the windows up while revving, idle, and hard throttle. The video ends with a drive by in first and second. You can hear the car stuggling to get traction and this is not on runflats.



Conclusion

This has been a mod I have held off on for a while. I have to say that I am extremely pleased I made the plunge. Bimmerworld was extremely easy to work with and helpful beyond description. Their sales people are knowledgable and their "buy to ship" process went flawlessly. Bimmerworld also brought a stainless steel tip version of the HKS exhaust to us, which I think is a must on this exhaust. Bimmerworld has introductory pricing on $1649 and that is simply unbeatable for an exhaust of this quality!

The power is absolutely noticeable especially at high rpms and the sound is intoxicating. It is smooth as silk and quiet idle. Get on the gas and the sound opens up to a fully deep, throaty sound that is fully compatible with our BMW elegance.

Finally, HKS has out done themselves on this exhaust. They have really excelled with:

1. Stainless pipes
2. Spot-on Fitment
3. CNC flanges
4. Spotless welds
5. Gorgeous HKS muffler flex plate
6. Bomb-proof gaskets
7. All necessary hardware

Thanks HKS and Bimmerworld for making this an incredibly satisfying purchase!

[flukey]

i want this.....

[lpphreakx06]

Looks 100x better than the ti burnt tips.

[dkvby]

look awesome. 1 of the best lookin+performance

[ra2fanatic]

the left side looks to be off center of the bumper exhaust cutout.

[Former_Boosted_IS]

Originally Posted by ra2fanatic

the left side looks to be off center of the bumper exhaust cutout.

I think you are referring to a picture while I was going through the final alignment. Here is the picture after everything was aligned:



Trust me, if I shoot straight on to the pipe, it is perfectly aligned in between the cutouts. I can take that picture again tomorrow if you want.

[TurboSid]

great review as usual

[PaulBailey@ltbmw]

Great review

[BillLee]

wow beautiful

[jrsbeamer335]

wow everything on it is spot on!

[Alan l.]

More pics vids please@!

I want to see how the tips look further back from the car. Also, does the exhaust sound too much like stock at any rpm or does it sound completely different?

PM what the total came out to with shipping

Thanks!

[AvZbMvE]

awesome review! i didnt know they had the SS tips...they look much better than the blue tips!
great job

[Former_Boosted_IS]

Originally Posted by Alan l.

More pics vids please@!

I want to see how the tips look further back from the car. Also, does the exhaust sound too much like stock at any rpm or does it sound completely different?

PM what the total came out to with shipping

Thanks!

Alan, the sounds is much more throaty than the stock exhaust. This is a smooth throaty aggressive sound. None of the gurgles or metallic sounds that a lot of similar setups have.

[mkPOTO]

badass exhaust, i will be picking up one very soon

[Kelvin1000]

Congratulations on a great purchase!!!

[Alan l.]

Originally Posted by Former_Boosted_IS

Alan, the sounds is much more throaty than the stock exhaust. This is a smooth throaty aggressive sound. None of the gurgles or metallic sounds that a lot of similar setups have.

Yeah I was worried that this exhaust is too quiet and can't even hear it above the engine noises. I use to have a supersprint on my e46 and that thing was as quiet as stock. I had to cut out all of the resonators just to hear it a little. Choosing between this and the AE exhaust just got alot tuffer!

Alan

[YellowFinger]

hands down the best exhaust out there for the 335i

best looks
best performance
best quality

great price

[YellowFinger]

Originally Posted by Alan l.

Yeah I was worried that this exhaust is too quiet and can't even hear it above the engine noises. I use to have a supersprint on my e46 and that thing was as quiet as stock. I had to cut out all of the resonators just to hear it a little. Choosing between this and the AE exhaust just got alot tuffer!

Alan

Alan,

please dont even mention AE and HKS in the same sentence. HKS is in a totally different league.

[5soko335i]

AS always man, AWESOME write up and review!

Can we get some pics from behind the car shwoing the exhaust installed and TIPS

[Boost Gomez]

Absolutely beautiful exhaust.

[Sparky66]

Thanks for the great review........................I'm sold

[chumley]

Thanks for the amazingly thorough review. I'm sold!