Results of CGT Exhaust Experiment

Jim Green
Tue, 13 May 2003 07:29:27 -0700 (PDT)

--- David <> 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

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