Flowmaster, the worst possible choice?
Flowmaster, the worst possible choice? Does anyone have any hard evidence that the standard Flowmaster 40 series catback for LS1 F-bodies really is as bad as people say? I say this because... my car has it and I'm not sure what I want to do with it.
If it really is THAT terrible, I'm going to see about changing out the muffler and keeping the pipes hung, unless a whole new catback would be in order? Thoughts on this would also be nice. Also, Flowmaster + A cut-out perhaps? Would the sudden massive difference(assuming Flowmaster does suck) in flow perhaps throw the tune off if I just flipped open the cut out?
Any help at all is appreciated!!
If it really is THAT terrible, I'm going to see about changing out the muffler and keeping the pipes hung, unless a whole new catback would be in order? Thoughts on this would also be nice. Also, Flowmaster + A cut-out perhaps? Would the sudden massive difference(assuming Flowmaster does suck) in flow perhaps throw the tune off if I just flipped open the cut out?
Any help at all is appreciated!!
TECH Regular
Joined: Sep 2006
Posts: 447
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From: Houston
Yes, flipping open the cutout would make you run lean and put your timing off a lil. Unless your car is tuned for the cutout open you probably wont get any power from it. The flowmaster does hold the car back once you have headers and start to get above 5500 rpms.... something a lil freer flowing like a magnaflow muffler would help.
A cutout will essentially bypass the muffler (although some exhaust will still flow through as I've found out through my own experimentation), so yes, any losses associated with the Flowmaster muffler will be negated.
The Flowmaster is my favorite sounding exhaust on stock exhaust manifolds and cats...it is too bad it doesn't perform like it sounds.
The Flowmaster is my favorite sounding exhaust on stock exhaust manifolds and cats...it is too bad it doesn't perform like it sounds.
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Verdad Gallardo That is the biggest misconception out there for these cars...if I had a nickle for every time someone asked me if I had a Flowmaster exhaust, I'd be rich...instead, I just have a nice look of disgust when someone asks me that, and I get the question constantly.
TECH Fanatic
Joined: May 2005
Posts: 1,135
Likes: 1
From: The 'Burgh, PA
Yes, flipping open the cutout would make you run lean and put your timing off a lil. Unless your car is tuned for the cutout open you probably wont get any power from it. The flowmaster does hold the car back once you have headers and start to get above 5500 rpms.... something a lil freer flowing like a magnaflow muffler would help.
You do not have to tune for a cutout - they make power right out of the box. The flowmaster does sound good, but there are so many other exhaust setups that sound good and flow. Why not go with some of the proven winners like magnaflow, hooker, SLP, Corsa, GMMG, duals, ect? 
I picked up 17 lb-ft and 15hp down low and about 12 hp/tq at peak with cutout open vs. closed with flowmaster.
Another bad thing about the Flowstopper is that they almost always rust out from the inside and you will start to get resonance. The only good points about the Flowmaster are that it's cheap and easily available.
I'll be yanking mine out and putting duals on, hopefully while I'm home over Christmas.
Another bad thing about the Flowstopper is that they almost always rust out from the inside and you will start to get resonance. The only good points about the Flowmaster are that it's cheap and easily available.
I'll be yanking mine out and putting duals on, hopefully while I'm home over Christmas.
To bad though, as they could use a good engineering department. 
LOL! 
TECH Resident
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From: Tree-Hugging, Bug eating CALI'
i had a flowmaster with cats and stock manifolds sounded good. but then I went to Long tube headers and off road y pipe and its sounded like crap. I have a hooker cat back and I gained about 15 rwhp over the flowmaster. I dynoed before and after.
before flowmaster 312 rwhp/ 317 rwtq
after hooker cat back 327 rwhp / 321 rwtq
before flowmaster 312 rwhp/ 317 rwtq
after hooker cat back 327 rwhp / 321 rwtq