Exhaust question

[jiangtao75]

I am not really looking to kill trees and the ozone, but I was wondering what kind of horse power gains would one have after installing a true dual exhaust system on an early '86 model have? I am getting ready to turn my '86 into a weekend driver/showcar and my first project is to change the exhaust pipes that are suffering from rust { not to mention an exhaust leak due to the rust }. Is there any thing else I need to be aware of in taking on this task? Also, Im thinking about buying the $249 kit from Mid America that is pretty much a true dual without the cats. Thanks!

 

[sxyvet]

hi there jiangtao75,
you should also look at buying a good set of headers such as tpis or hookers plus add a x-pipe cross over and defienetly run a true twin system for sure along with a good set of free flowing straight thru type rear mufflers such as magnaflow or borla!
another good feature is to run 2/1/2" mandrel bent pipes as well!
i also decided to keep my cats to keep the boys in blue(cops) happy but went with hiflow/high performance though type cats for better breathing!
all up running the above you at least get 25 plus horespower or more!
just a start any way mate!
good luck mate
glen
sxyvet
australia

 

[WhalePirot]

You have one cat.

Change in stages, if you prefer, but I suggest coated headers and Flowmasters (or another) to muffle. 'Hi-flow' cats are available, if you need, but butt-testing my (previous) warmed-up stock motor w/ and w/o the CAT made no discernable diference. At the time, I ran headers and Flowmasters, plus a hotter cam and more air into the CrossFire.

You can check the thread on tampering with emissions, but I believe it is a Federal (EPA) offense to run on the street without cat(s). True duals expose you to that while offering little or no performance, IMHO, to a mild motor.

 

[jiangtao75]

Well, I have one main cat and two pre cats. I am not really looking for a ton of horsepower, but just looking to replace the exhaust system in the cheapest and easiest way. My main concern was about the car throwing codes and what not plus how much louder the exhaust note would be. I already have flowmasters on it and the sound from inside the car can be a bit loud at the lower RPMs. Thanks, guys!

 

[Vettefan87]

You can remove the entire exhaust system, meaning take off all of the cats and it will still not throw a code as long as you have the O2 put back in the exhaust somewhere. All the O2s do on the earlier C4's is monitor exhaust gases coming out of the engine, not the cat.

 

[Mad-Mic]

how loud will it be?

http://www.corvettekillstories.com/photogallery/albums/Mad-Mic/Racing/Sweet_Sin.wmv

thats with out cats. total HP gain with long tube headers was about 50 rwhp from 100% factory stock exhaust on my 87.

 

[Vettefan87]

how loud will it be?

My mom can hear me leave the gas station down the street in my car :L.

 

[Mad-Mic]

My mom can hear me leave the gas station down the street in my car :L.

over a mile away my dad heard me leaving his house one night when i flogged it thru 1st and 2nd....lol

 

[Robertwav1]

In my day I attracted a lot of attention also...cops use to come out of my trunk...so I thought. Interesting to read about the upgrades in exhaust. Want to keep it as quiet as possible yet unleash as much HP as possible. Are the Hi perf cats legal? Do they add to the noise?

 

[Mad-Mic]

Are the Hi perf cats legal? Do they add to the noise?

yes and yes

 

[Robertwav1]

Okay guys, I got another question here about the exhaust. I called a shop yesterday, it's an exhaust shop that I had dealings with before with other vehicles. They tell me that the exhaust needs to be done first from the cats, back before the headers and the balance. I like the headers from TPIS that mount from the bottom for the C4 but I don't see the Y pipe for my car that they say you need. Need a little guidance here as to what to do first. Also need to find someone to do this work for me in NJ. Input appreciated.