Any HP gains with Stock Mufflers vs Flowmasters?

[03Sleeper]

Hey guys I'm trying to get some info for my buddy.
Is there any HP gains from Replacing the stock Mufflers
He's got a X-pipe with cats but stock Mufflers????
Should he replace the mufflers??
If so Whith what Flows or ?????
I say No But He thinks he will see more Tourqe and 2-3 Hp??
Is this true?
Thanks
p.s.
I got Parts from Ronnie!

 

[mrvax]

Well, Bierbelly from this site had Flowmasters welded into the stock system and lost 6-8 rwhp. I forget the exact #. Shoot him a PM.

 

[wms004]

Hey guys I'm trying to get some info for my buddy.
Is there any HP gains from Replacing the stock Mufflers
He's got a X-pipe with cats but stock Mufflers????
Should he replace the mufflers??
If so Whith what Flows or ?????
I say No But He thinks he will see more Tourqe and 2-3 Hp??
Is this true?
Thanks
p.s.
I got Parts from Ronnie!

2-3 hp if not 0 would be logical. Get flows for the sound. straight thru mufflers in Some cases get 2-3 more hp than flows.

-wade

 

[jrc_03_gt]

get the original 40 series flowmasters! They are great!

 

[Mr GT 02]

Get the Flowmaster American thunder cat bak system... 2-1/2" pipes (Mandrel Bent) and 3" tips!

end of posts!

 

[slow87GT]

when I had my mufflers done I didn't gain a thing, actually thought I lost some low end

I would leave stock mufflers, tell em to get a plenum or something else

 

[Rio96]

I just don't believe that lowering backpressure lowers
engine performance.(perhaps someone has a pic of a
cut up stock muffler)
IMO, the big problem is the stock muffler, not the tubing.
'whatever happened to glasspacs?'

 

[DELOS02GT]

I just did the mufflers and didn't notice anything but the sound. The mid-pipe will give you the HP gain....not the mufflers.

 

[Too Slow]

whenever i had the original flows welded in my 02 auto Gt i noticed an immediate gain. wasnt' much but it was there and i loved the sound.