I was at the dyno this past Friday and my car only picked up 2 hp over the gmmg. And a friend of mine did not pick up any over a hooker cat back.

Just for your info.

 

im keeping my single in single out.....the 427 should sound nasty through those

 

I picked up 21 hp and 14 torque with the cutout open on my old setup. This was over a hooker muffler.
Here's the dyno sheet. http://i16.photobucket.com/albums/b3...race/dyno1.jpg

 

I picked up 60 rwhp with my cut-out. I had a used catback. I was told it was a spintech, but I can't be sure. I went on the dyno after LT's, cam pulley, tb etc and had less power than stock. I was a little freaked out, then we opened the cut-out and picked up 60 hp. I took the pos catback off and put a magnaflow on.

There must have been a collapse in the muffler that was just insane.

 

I had a 4" mufflex catback with a Spintech muffler on my old car, It sounded bad *** but I lost 29rwhp and 34ftlbs going through it vs. a cutout.

 

i use to have flowmaster (dont know which one, the car had it when i bouth it) but i went from 478/444 to 518/487.. sure enough i was told that flowmaster sucked.. since then i switched to magnaflow which by the way made the car sound not as loud wich was what i wanted but when i redynod to see the difference it was minimal.. i only gaind like 2hp and 10rwtq.. overall iam happy on the switch and would recommend magnaflow

 

I got an 80 Flowmaster on mine. I just did my cam. Should I replace it or get a cut-out and if so with what. I really havent researched them much. I will be going to get it tuned in a few week and I guess that will determine what I do with it. I didnt realize how much the flowmasters choked up our LS1's.

 

any results from a dynomax?
3" in dual out.

 

I gained 2rwhp/2rwtq with cutout open over my hooker...

 

with the mods in my sig I gained 2 MPH with a cut out

 

flowmaster cross chambered mufflers are what chokes.....flowmaster single in single out are great!

 

I guess I should be getting a cutout. My car came with a chokemaster. I like how quiet it is, so I'll keep it for daily driving.