George45

The 1990 dk.red metalic / tan I just bought has a muffler coming apart on the inside so I am look to see what others may be using. I don't want anything loud or droning. Prefer pretty much a stock type replacement. Found a lot of louder reviews and drones but nothing much else.this is not a show car or points chaser. Pretty much a driver in nicer weather. Ideas?

Thanks

Crabs

I have a Flowmaster cat back system on my '90 and love it.
No drone, and although louder than stock, not too loud.
BB and Corsas tend to be louder at WOT, about the same at lower RPMs.

'Crabs
'90 ZR1 #792

mike100

which muffler is going out? I want to replace my 1990 left muff. it rattles and buzzes at resonances around 1900 rpm.

FASTAZU

Have Flows on my 93 Corsa on 91 No Drone on ether. You could always find 93-95 stock set-up better flow.

George45

The left as well.

Geotge

billschroeder5842

I'm interested in this topic as I (continue my angst) want/need to do something with my stock '91.

I'm intrigued with the idea of removing the center resonator and replacing it with an "X" pipe. However I don't want any drone.

I'm not sure if to leave the stock muffler or swap them for something different?

ZR1Bob

George, since a lot of folks switch to aftermarket systems there are many removed stock systems available for little money if you want to stay stock. After years of aftermarket systems (mostly Corsa) I finally went back to stock with a pair of electric cutouts just in front of the mufflers for when I wanted to have an unrestricted exhaust My 95 system's resonator is not restrictive; just the mufflers. The 90's center resonator is quite restrictive but like all the center resonators it handles the resonance at 3,400 rpms so don't just remove it. --Bob

ghlkal

I have Corsa on my 90. What I especially appreciate is that there is absolutely no drone. I can cruise and have a conversation with my wife. When you get on go-pedal, it's loud, but otherwise it's very civilized.

LT5corsa

I'd make sure that the Cats aren't coming apart and collecting in the muffler...

Check that before you change the exhaust (if for that reason only). I think Corsa or B&B fusion are AWESOME upgrades with NO drone!

Good luck and curious to see what is actually coming apart.



David

George45

We are sure so far that there is a loose pipe in the muffler. 7yoy can make it rattle if you strike it with your Hand. The car should arrive next week if they ever pick it up. So we will hopefully figure it out then.

90z

I have an NOS set of GM replacement ZR1 mufflers available if you're interested. P/n 12511525 and 12511524. Let me know.

billschroeder5842

My .02 from what I've learned about ZR1 mufflers...

There was a design change and 91 and up mufflers are more desirable as the 90 has an oval inlet (slightly restrictive) and the 91 and up are round, matching the exhaust pipes and with less restriction.

Also, the 90 and 91 resonators are very restrictive with the 92 and later years as almost zero drag. The inside diameter of the 90/91 resonator is 1 5/8 while the 92 and up match the exhaust pipes at 2 5/8. Marc Haibeck reports that the 90/91 resonator accounts for a -10 HP.

BTW... Chevrolet used the same 2 5/8 resonator on 92s on up. So an LT1, LT4 or a Zr1 resonator will work equally. I'm swapping my 91 resonator for a 93 version next Friday.

Might want to consider doing a twofer?

Mr. Gizmo

i recall the 1990 and 1991 zr1 cats had a problem with reverse ingestion into the motor when at wot then when the driver let off the gas the contents of the Cat would suck back up into the motor causing catostrophic engine failure .

In either 1992 or 93 there was a redesign of the cat so this wouldn't happen.