Seight

I know a lot of you have modified your exhausts so hopefully someone can answer my question: My rear silencer, I believe it is referred to as the primary silencer/muffler which runs across the back of the car is buzzing slightly at idle so I am going to get this sorted out. If I replace this silencer altogether with the bypass pipe that is for sale in various places, how much louder will the system be? I don't mind a sportier sound but I don't want some over-bassy noise that sets alarms off and is loud inside the car and so on. A subtle difference is OK and I will go with that but I don't want a huge change in the sound the car makes. Can any of you advise from your experience?

Thanks
Alex

springer3

I had the same concerns when I installed the primary bypass. I am very happy with the new sound. I can still listen to the radio in the cabin, but there is a nice snarl at WOT. I am in a townhouse complex that has a "no loud mufflers" policy. Nobody complained, although I am careful as I come and go.

I have a low-mileage primary muffler you can have cheap, but I guess shipping to London might be prohibitive.

RonCT

My "new to me" C2 has just one silencer - the long one behind the rear bumper. Where the 2nd muffler was is just air space now with a "G" pipe to the exhaust tip. Cat bypass too. The sound is intoxicating. You can easily control it by keeping the revs low, but when you get into the higher RPMS and / or give it lots of throttle, the sound is amazing. Deep, burbles, and not at all obnoxious...

boxsey911

Greg L put together a nice little selection of the sound of different configurations that you can find here:

http://members.rennlist.com/greg_l/964ex.htm

Gus

One thought for consideration in replacing the primary muffler with a by-pass pipe and keeping the secondary muffler was the weight advantage - You are saving a lot of weight that is hanging off the rear end of the car when you replace the primary with just pipe - As long as you keep the CAT the noise is not too excessive - remove the CAT and you get into a really nice tone and a little extra ponies - still able to live with the sound and under 96db - unless your secondary is really shot - I have a cab so the sound probably comes through more - but I really enjoy it -

Don Nguyen

How loud would it be if I had a straight through system. No cat, no primary, and no secondary? Or should I at least keep one of the three in there?

Seems like something an exhaust shop can always fab up for me, instead of spending such a large amount on pre-made straight through pipes. I can understand paying a lot for mufflers with something inside their cores, but not just regular/bent pipes.

Ritter v4.0

I've run with all three deleted. Way too loud- and I like loud. Just a stock CAT is the threshold for me (about 94db at idle) but I worried about the restrictiveness so I inserted a HF cat. Too loud again- +100db.

I'm working on a lightweight freeflow primary muffler in concert with the HF CAT- I hope that will be the answer in terms of low weight, least restrictive and acceptable sound level.

garrett376

Here's a fun clip of some interior noise with a cat bypass, primary in place, secondary bypass... Listen to that 4000RPM intake howl!

poor man's dyno run

N51

I went from stock to a primary bypass, then added a cat bypass. Not loud at all. Easy to live with on 800-900 mile days. But...and I'm sure to be in the minority thought here, I miss the whirl of the valve train when cruising at higher speeds. While not unpleasant, so much is lost.

Don Nguyen

What's the overall best power/weight gainer to loudness set up then?

Ritter v4.0

Don't forgot cost. And are emissions and heat a factor?

The best exhaust might be nice dual headers into a single HF (primary) exhaust, but that could be expensive, not pass emissions and still too loud for your neighbors.

tbennett017

Its a very subjective choice. I have tried them all, and a single primary bypass is where I ended up. The best balance for me of exhaust sound while capturing the uniqueness of the engine. Its what all the local rice-jockeys wish they had from their Hondas...

etom

I think I've tried a couple of combos.
Stock = a tad tame.
Primary by-pass only = not bad, at least a bit more character.
Primary bypass + cat bypass = pretty good, a hint of little rumble, not too loud from the inside, and perhaps a bit of noticeable power increase.
Cat bypass + g-pipe (secondary bypass) = a lower rumble, a little louder, a little more noise on the inside.
All bypassed = WAY TOO LOUD for life on this planet.

DLCrow

I might suggest you check out the tech section of PCA.org. A year or so back, Joel Reiser advised that between the two, removal of the secondary was a slight winner between the choice of the two - he further noted that taking both off, removed actually resulted in a slight decrease in HP as the stock chip didn't work well wit hthe change in back pressure. As a result, i removed my secondary - replaced with the traditional G-pipe - got great sound (I can idle at a light in downtown DC in rush hour and not attract too much pedestrian attention!)

Last observation - a local DE instructor recently advised that the next HP advantageous thing would be to surgically remove most of the air box cover (leaving the frame only) - increased intake airflow - some increase in noise, but not bad.

Good luck

RonCT

You are talking about the "Cup Airbox" modification. US Cup cars had no "top" airbox cover - my shop just cuts the top off for the same effect. You just need the software to run things properly - for example, I have a Steve Wong chip and the Secondary and Cat bypass - works very well together.