Originally Posted by Pro Stock John

This was posted on www.fullsizechevy.com which is a truck forum. Supposedly this review was performed by Martel Brothers...

*******************
All tests via an independent lab
All tests @ 15” wc

2 “ Straight Pipe 283 CFM
2 ¼ “ Straight Pipe 365 CFM
2 ½ “ Straight Pipe 521 CFM

2 ¼” Typical Bent tailpipe 268 CFM
2 ½” Typical Bent Tailpipe 417 CFM

2 ¼” Inlet/Outlet_ Glass Pack Tips- No Louvers- Smooth 274 CFM
2 ¼” Inlet/Outlet- Glass Pack Tips-Louvered 133 CFM
Same as above set for reverse flow 141 CFM
2 ¼” Cherry Bomb 239 CFM
2 ½” Cherry Bomb 294 CFM

2 ½” Inlet/Outlet Dynomax Super Turbo 278 CFM
2 ½” Inlet/Outlet Ultraflow Bullet 512 CFM
2 ½” Inlet/Outlet Gibson Superflow 267 CFM
2 ½” Inlet/Outlet Flowmaster ( 2 Chamber) 249 CFM
2 ½” Inlet Outlet Flowmaster ( 3 Chamber) 229 CFM
2 ¼” Inlet/Outlet Thrush CVX 260 CFM
2 ½” Inlet/Outlet Maremount Cherry Bomb 298 CFM
2 ½” Inlet/Outlet Hooker Aero Chamber 324 CFM
2 ½” Inlet/Outlet Hooker Max Flow 521 CFM
2 ½” Inlet/Outlet Borla Turbo 373 CFM
2 1/2" Inlet/Outlet Magnaflow 284 CFM


Standard OEM 2 ¼” Inlet/Outlet 138-152 CFM
Standard OEM 2 ½” Inlet/Outlet 161-197 CFM

The madrel bending of the pipes done by aftermarket exhaust companies is good for 2-4 h.p. depending on the severity of the stock bends. Most local exhaust places dont have a mandrel bender so changing the pipes out doesnt do anything if pipe size it not increased.

My opinion, if its more noise and a little more power just add the best flowing stainless muffler to the current system and never do it again. If you increase pipe sizes, then a local shop and only stainless. Dont care about money but want ease and better gains than most local shops can offer with no pipe size increase, and aftermarket exhaust.

NOISE does not mean power, some think it does is why Flowmasters are sold in the numbers they are!!!

Originally Posted by FAST LS1

Thought I would add this review too.

The results in HP order:
1.Flowtech Warlock (open) 374.2 hp/ 333.1 tq
2.Bassani Real Street 373.7 hp/ 333.8 tq
3.Hooker Maxflow 373.5 hp/ 333 tq
4.Borla XS 373.3 hp/ 332.6 tq
5.Magnaflow 372.8 / 332.5 tq
6.MAC 372.3 hp / 331.5 tq
7.Flowtech Afterburner 372.3 hp/ 330.1 tq
8.Hooker Aerochamber 372.1 hp/ 330.4 tq
9.Bassani 372 hp/ 333.5 tq
10.Spintech 371.6 hp/ 332.2 tq
11.Edelbrock Performer RPM 370.9 hp / 331.3 tq
12.Borla XR1 370 hp/ 334 tq
13.Flowtech Terminator 369.5 hp / 331.3 tq
14.Dynomax Ultra Flo 369.4 / 333.2 tq
15.Flowmaster 369.4 hp / 331.8 tq
16.Flowtech Warlock 366.3 hp / 325.3 tq
17.No muffs 365.2 hp / 330.1 tq

Sound Off in Quietest to Loudest (Decibels):

1.Borla XS, 80db at idle, 90db at 2,000 rpm, 110db at WOT.
2.Hooker Maxflow, 80db at idle, 90db at 2,000 rpm, 120db at WOT.
3.Magnaflow, 82db at idle, 91 at 2,000 rpm, 114db at WOT.
4.Flowmaster, 82db at idle, 93 at 2,000 rpm, 115db at WOT.
5.Flowtech Warlock, 83db at idle, 92 at 2,000 rpm, 112db at WOT.
6.Dynomax UltraFlo, 83db at idle, 94 at 2,000 rpm, 113db at WOT.
7.Borla XR1, 83db at idle, 96db at 2,000 rpm, 118db at WOT.
8.Bassani Street, 83db at idle, 96db at 2,000 rpm, 120db at WOT.
9.Edelbrock RPM, 84db at idle, 93db at 2,000 rpm, 118db at WOT.
10.Bassani Real Street, 84db at idle, 96db at 2,000 rpm, MAX. (120+db).
11.Flowtech Afterburner, 86db at idle, 94db at 2,000 rpm, 115db at WOT.
12.Flowtech Terminator, 86db at idle, 94db at 2,000 rpm, 119db at WOT.
13.Hooker Aerochamber, 87db at idle, 94db at 2,000 rpm, 114db at WOT.
14.SpinTech, 87db at idle, 97db at 2,000 rpm, 116db at WOT.
15.MAC, 87db at idle, 98db at 2,000 rpm, 119db at WOT.
16.No Muffler, 91db at idle, 103db at 2,000 rpm, MAX. (120+db).

http://forums.stangnet.com/archive/index.php/t-392314

Originally Posted by FAST LS1

I found another flow test comparision.

http://www.svtoa.org/articles_006.htm

MODEL
Flow Rate Muffler Inlet Size

@ 20.3" H2O

+ Edelbrock 5501 492 scfm 2.25"
$ Flowmaster 42440 483 scfm 2.25"
Race Magnum Welded 17216 711 scfm 2.25"

+ Edelbrock 5511 579 scfm 2.50"
$ Flowmaster 42540 352 scfm 2.50"
Ultra-Flo SS 17263 1133 scfm 2.50"
Race Magnum Welded 17218 1000 scfm 2.50"
# Borla 40600 836 scfm 2.50"

+ Edelbrock 5505 708 scfm 3.00"
$ Flowmaster 43040 392 scfm 3.00"
Ultra-Flo SS 17296 2200 scfm 3.00"
Race Magnum Welded 17220 2200 scfm 3.00"
# Borla 40450 1400 scfm 3.00"
# Borla 40575 1100 scfm 3.00"

@ Edelbrock 5535 562 scfm 3.50"
$ Flowmaster 435409 576 scfm 3.50"
Ultra-Flo SS 17268 2200 scfm 3.50"
Race Magnum Welded 17224 2200 scfm 3.50"
# Borla 40615 854 scfm 3.50"

@ Edelbrock 5537 1400 scfm 4.00"
* Flowmaster 54040-10 634 scfm 4.00"
Race Magnum Welded 17225 2600 scfm 4.00"
# Borla 40741 1450 scfm 4.00"

+ Edelbrock General Application Series
@ Edelbrock Victor Series Race
$ Flowmaster 40 Series ( 2 Chamber)
* Flowmaster Delta Force Race Series
# Borla XR-1 Racing Series (Round or Oval)

Originally Posted by Keenov

As in 2.5" compared to 3"? I saw a muffler thread, that's about it. Use the search button, you have been here long enough.

Originally Posted by Jammer

Spent hours searching! You know that! Not saying I didnt miss it...just saying I didnt find it. Guess my vocabulary switch was in the off position.
But thanks for the info and thanks for busting my *****. But..beleive it or not, that didnt help too much...need to compare 2.5 to 3 to 3.5 to 4 and curious if oval pipe slows CFM due to disrupting any possible swirl. As far as mufflers...my only mufflers are turbos...