Hey all, I have a small dilemma and I'd like to get your guys' opinion...

I have a street-ported 3rd gen non-seq TT with dp, mp, and race exhaust. Dam, is this car loud. Anytime I have the throttle depress to 1/4 of the way, I feel like the whole world is watching (most of the time the sleeping world are the ones that get pissed), which is bad because there's a lot of cops by me.

I need help in finding a way to 'silence' the decibel output, without compromising airflow. I DO NOT want to take off any of my power-producing bolt ons so here's a few solutions I was thinking about:

1) Get a Hi-Flo racing 'cat' and weld it somewhere between my midpipe and exhaust. Are there any drawbacks? Are Hi-Flo racing cats restrictive in any way? Do you guys think this kind of frankenstein exhaust will hurt my car?

2) Same as # 1 except instead of a Hi-Flo race cat, I'd just weld another muffler.

3) Leave the frankenstein exhaust idea alone and get a SuperTrapp muffler system (or something similiar) with the ability to 'tune' the decibel level by adding and removing disks in the muffler. I know this will change my HP and torque depending on how many disks I have in the muffler so I'm not too fond of the idea of varying the backpressure in my exhaust.

Any suggestions would be appreciated. Thanks for your time.

R1R

 

This just does not make sense. If you are going to have a hi-flo cat in there, just replace the midpipe with it and save yourself from trying to re-engineer something.

 

While a cat will quite down the exhaust, a pre-silencer would probably do the job, and you will probably end up with more power then going with the cat..


Course the cat is probably better for the environment.

 

My mistake, I didn't mean an actual Racing Cat - what I meant was a silencer that looks like a cat so to resonate the sound before it exits my cat-back.

Is this the best alternative?

 

What you want is a resonated mid-pipe..


Or you could just get a pre-silencer and have someone weld it it to your mid-pipe..


BTW if you get one packed with fiberglass it will only last ~6 months. where one packed with SS wool will last longer because rotaries exhausts are very hot.


-Zach

 

Thanks for your input Zach. You helped.

R1R

 

like zach said .......resonated midpipe, nuff said

 

Resonated midpipe will help a little and just about anything else will hurt performance. If you want something quite go with the racing beat dual tip catback and a high flow cat. The rb catback will help out a bunch but it will restrict a good bit of air flow - you do have a compromise somewhere along the way.

 

if you have an exhaust that came with a silencer like the apex'o gt-spec, you could put it in when ya leave and when ya get away from your neighbors, take it out and put it in a heat safe container in your car. then when you approach ur neighborhood, reverse the process. seems like a lot of hassle, but you won't kill any of your performance and your neighbors will be happy again, just my 2 cents

 

Just stuff a T-shirt in your exhaust. Seriously. It won't hurt a thing. Chicks dig it when you put it on after a couple of weeks.

Potatos work really well also, just stand clear or your nuts will turn into tater tots.

It has been my profound experience in life that everything that is really loud - is REALLY slow, like Civics, Harleys and diesels........

Of course top fuel dragsters are an exception.

 

Any thoughts about supertrapps?

 

I know a guy who had a cutom homemade 'bypass' exhaust. Ok - he had a stright pipe from the downpipe back and it split with a block-off plate to either go to the straight pipe or to the pipe with the muffler on it. He has a switch to cross it over. It's pretty cool, his car is freakin cool

 

Yeah it's called a cut out. Is that safe for our cars? Don't you have to have some back pressure?

 

hahahahahaha, the turbos put a helluvalotta backpressure on the system. only reasonb you need any after that is cuz the compter cant handle to quicker spool/creep/spike w/e

 

"If it's too loud, you're too old."

 

you can always go to summitracing.com and look for a silencer (they come in all different sizes so you should beable to find one for your catback) they sell if your catback does not come with one. just slip it in to your catback at night or before you park and idle on your street like spooling93R1 said

 

nope, you dont need any back pressure as long as you get on a dyno and tune for the low/no backpressure. The torque curve and hp curve should look better then the stock, if not, your not tuning right

 

yup, the only thing having the cutout might affect is if u dont let it cool down u can get cold air up in the turbo easier, = bad, but i run a striaght downpipe, so i dont have ne problems yet, ya jus gotta be patient when u turn ur car off to idle a while, but that cutout sounds nice

 

doesnt an exhaust cutout create different boost levels when its closed and open? i believe thats what happened to a member on another forum (with a civic si, though)..... i would think that the fd would have a problem with changing boost levels due to the change in air/fuel requirements, no?

 

Go sequential. The stock sequential turbo system has a really nice feature of making the car quiet below 4500 RPM.

Get a muffled midpipe. Or weld a SS muffler from Summit, Jeg's, etc. into your existing midpipe. Do a search for muffler comparisons. All the good ones seem to flow about the same, but the noise levels can vary widely. 5.0 Mustang & Super Fords tested 15 mufflers recently and had dyno and sound level results in an article. The new Borla ProXS mufflers made good HP, should last, and were nice and quiet, for instance. I don't think you can get 3" center/center, but they do have a 3" center/offset version.

Make a midpipe that splits into two pipes and then back into one before the cat-back. One pipe will be 2" and contains a quiet (but durable) muffler. The other pipe is 3" and contains an electric exhaust cut-out. It won't dump to atmosphere, but opening the valve would allow exhaust to flow through the bigger, free pipe. You could operate it manually, or even get an RPM switch to run it automatically. Or just get a cable cut-out first to see if it is worth investing in an electronic valve.

These places sell electric cut-out valves:
http://www.dougsheaders.com/online_s...ail.cfm?id=217
http://www.buickgn.com/electricexhaustcutout.htm
http://www.quicktimeperformance.com/qtec.htm (link is broken right now)

RPM switches are available from Summit, etc.

Note that changing the exhaust system will change the boost control. It will also change your mixture (it will be leaner with the valve open for a given set of fuel maps). Using an RPM switch to open the valve has the nice feature of allowing you to make the map good for the whole range. The other safe alternative is that you can tune for the open valve and it will run a bit rich with it closed.

-Max

 

Just put one or two pre-silencers in there.
A pre-silencer is BASICALLY just a mini-muffler. Brands don't seem to matter very much when it comes to these, as long as construction is good and size is proper.
This won't lower your power output much that you would notice, but will make your car a lot quieter.
I estimate that a pre-silencer only adds about 1-2 psi of backpressure.

 

I have a little silencer in my cannon, its the apexi n1, it came with this little silencer, prob makes it %50 quieter...

 

The nice thing about Supertrapps is they are tunable and their distinctive look. The bad thing is they are restrictive.

 

.I think Supertrapps are only restrictive if you run a couple caps... A friend of mine had an original prototype kevin wyum exhaust that was basically a straight pipe from the downpipe back to a 5" supertrapp. He ran it with sequential turbos AND a precat, and without caps its still the loudest thing i've ever heard... you could hear it a half mile away.... and it was a deep, rich sound unlike some of the japspec fart cans... sounded like a really large superbike.

I don't think it was the least bit restrictive without (or with many) caps... but then again it wasn't quiet either

 

bringing this thread back. does anyone have a cut-out on their car that would like to share and info? information reguarding power increasement/decreasement in either horse or torque, spool up time, tuning difficulty, and any boost problems like creeping. hopefully someone can shed some light here!