Glass packs
Safety Car
Joined: Oct 2008
Posts: 4,022
Likes: 30
From: Los Angeles CA
the po had these glasspack mufflers in the back behind the cat, tips look like zr1 tips, it was loud and it bothered me, i replace them with mamo stock looking ones with dual functionaing outlets, they look teeny (tips) campared to the glasspacks( which were blown out) but are alot quieter!!
and the fit is simply marvelous...
and the fit is simply marvelous...
Le Mans Master
Joined: Apr 2005
Posts: 6,413
Likes: 9
From: The Old Dominion
When I bought my '87 it had those Monza style glasspacks and the rest of the exhaust was stock. I thought it sounded nice, sort of smooth, deep, and exotic. I had to replace them because they failed inspection as they had no "can" and therefore didn't count as a muffler. The Flowmasters I replaced them with (those direct-fit C4 ones) were much louder and rumblier.
I don't see why it would "jack up" the performance, though what kind of exhaust system are you running currently?
I don't see why it would "jack up" the performance, though what kind of exhaust system are you running currently?
Team Owner
Joined: Mar 2001
Posts: 30,847
Likes: 293
From: Boston, Dallas, Detroit, SoCal, back to Boston MA
I've been running eliminator, straight pipes, for years now.
If you keep the cat's it's really not that loud
I did pick up a 3in system for when the LT's and blower go on.
If you keep the cat's it's really not that loud
I did pick up a 3in system for when the LT's and blower go on.
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Gotta say if you retain the cat there is no need for a muffler. I am however considered everly aggressive by my co workers. 
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
I've used g-packs on my vette in the past. Also tried with and w/o front cats. Consider leaving one of these two out if you're looking for a little more power. If it's too loud/resonate, then add the other back in.
HP gain would be small, but better than nothing. I'd vote for replacement of the old cats as more likely to gain some ponies. But, g-packs could help a little too. Each component in the exhaust system can be improved (with replacement/elimination) about 5-10hp for a stock motor.
CATs act like mufflers too.
HP gain would be small, but better than nothing. I'd vote for replacement of the old cats as more likely to gain some ponies. But, g-packs could help a little too. Each component in the exhaust system can be improved (with replacement/elimination) about 5-10hp for a stock motor.
CATs act like mufflers too.