sancho

I recently had to remove my gas tank on my '89 IROC, and since everything on my exhaust was welded (i.e. I couldn't unbolt the exhaust from the CAT like my Haynes manual said to), I had to cut the muffler off. After I had my gas tank fixed and everything put back together, I had to drive my car to the exhaust shop to have it welded back on. I immediately noticed that the car had more power than it did with the muffler on.

I didn't expect to see any power increases, however, because I have always thought that the stock manifolds and the CAT were the biggest restrictions on a stock exhaust. Plus, since I've even seen truck mufflers that you can look straight through from one end to the other, I didn't think that mufflers typically accounted for any restrictions at all.

As it turned out, when the guy at the exhaust shop welded the muffler back on, he told me that I had an aftermarket exhaust put on the car (which I didn't know but suspected). He said that my muffler was a Midas (or some other company that was actually Midas) and that my CAT was also aftermarket--and that both were essentially garbage and worse than stock.

Is it normal for a muffler to be a restrictive exhaust component (when compared to the CAT and manifolds)?

Thanks

jd13

Yes, mufflers are restrictive. Some more than others. Maybe 5 hp at the most from good aftermarket mufflers.

Why do you think people run cutouts?

sancho

My muffler must really be a restrictive one, then, because I don't think my "SOTP gague" is sensitive enough to notice just a 5HP difference--and I did notice a difference, just driving around town.

The guy that put my SFCs on also said that he has access to a lot of new/slightly used exhaust systems off of LS1 Camaros and Firebirds. Apparently, there's a lot of people who buy these cars and immediately start putting aftermarket stuff on them, so all of their original stuff goes up for grabs. He told me that he could get some great deals on these systems and install them on my car, too.

Out of curiousity, how difficult of an install would it be to put a fourth-gen exhaust (from an LS1 car) onto a third-gen Camaro? Also, would a fourth-gen CAT have the ability to accept an A.I.R. line?

I asked him how much he'd charge to do it, and his tentative estimate sounded great--but I wonder if he might have underestimated the labor involved...

1990GTA

I know exactly what you are talking about, my exhaust was also welded and I had to cut it off right by the rear end to do my fuel pump. When I took it to the shop to have the muffler welded back on the throttle response was awesome, and when I left with my muffler on I noticed a big difference. It was a new Dynomax super turbo, so it wasnt because of a clogged muffler or anything. Now I have long tube headers and a custom Y-pipe with no cat, I cut the muffler off again to put a Walbro fuel pump in and also unhooked the Y-pipe from the headers so I could drop the tranny pan easier (fluid & filter change,shift kit install). With the open headers the throttle response is unreal, when I get my tranny back together I plan to take it to the track before I put the exhaust back on just to see the difference. I will post some open header times and muffler times when I get them.

IROCZTWENTYGR8

iTrader: (1)

They restrict a little but not too much. People try to talk about how Flowmaster doesn't flow as good as others but it isn't a big deal. Hasn't stopped TRAXION from running his times and many others.

TransAmTBI

ANY EMMISIONS DEVISE IS RESTRICTIVE! muffler, cat, cat back!! all stink but thats the law!

is it really true that since states like florida dont have inspection they could do something like open hedders??


anyway anything past the block is restrictive but you need something to stop the engine bay from catching fire lol

1990GTA

is it really true that since states like florida dont have inspection they could do something like open hedders??


I'm sure if you got stopped you would get some kind of a ticket, maybe even just to get it fixed within 24 hours. You might even just get a warning. I have only driven my third gen once with open headers and didnt encounter any cops, but I used to have a 1978 Firebird with longtubes with little mufflers bolted right to the headers and it was real loud. I drove it like that for years and even got pulled over a few times for various things and they never even mentioned the noise, which really surprised me.

91RS5speed

I drove open headers for a week and didnt get pulled over and drove by many cops. I have a cutout right after the y-pipe that ive been leaving open. Just dont do any red line shifts by a cop and you should be ok.

FyreLance

Are you sure it wasn't your mind playing tricks on you?

I.E. louder must be faster? ;-)