Results of CGT Exhaust Experiment

[Jim Green]

--- David <duandcc_forums at cox.net> wrote:
> Patient: 1987.5 CGT (NG engine otherwise stock).
> Proceidure: Cut out bad center muffer, replace with
> traditional glasspack. The rear muffler was already
> removed and replaced with pipe a while back. So now
> the only silencer is a glasspack.
>
> Results: FANTASTIC! Nice LOW rumble under 3,000 RPM,
> sounds like a screaming banche at higher RPMs at
> WOT. At highway cruising speeds, it is only somewhat
> intrusive, but not to the point of annoying me or
> people in surrounding cars. I did make a guy in a
> 5.0 look over to see what the noise was (was reving
> out at WOT). Also I noticed that the engine seems
> more willing to rev out. Before there seemed to be
> no real reason to rev past 5,000 RPMs. The engine
> just didn't seem to make any more power, just noise,
> beyond that point. Now, it revs much easier and
> seems to actually be making power up to 6,000 (have
> never pushed it past 6,000).
>
> The tone is perfect IMHO, but I would ultimately
> like to find a way to keep the same tone but lower
> the decibles. This exhaust project was "temporary"
> as I'm quite sure the whole system will need
> replacing in the next 6 months. The long term plan
> is to do a 2.5" cat back system, with glasspack AND
> rear muffler. I would think that by having the
> glasspack as the "resonator" and a traditional
> (high-flow?) rear muffer I should be able to keep
> the tone about the same, just quieter. Or at least
> that's what I hope will happen. Anybody care to
> comment on my plan?

One glasspack is just not enough, especially on a NA
car.  I run a strait through 3" Borla and one 15" long
glasspack and the sound is awesome.  You can probably
achieve the same with another long glasspack.

=====
Jim Green
'89 90tq 034EFI, Haltech IG5
http://www.geocities.com/jeg1976/car_home.html

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