Just on a bolton car on a back-to-back same day/conditions dyno run, I gained 7hp 10tq between flowmaster 80 series catback and cutout. With the flowmaster on your car, there should be alot left on the table.

 

and the higher the hp the more gain you will see.

 

I ordered a pair of the new QTP oval low profile electric cutouts. I hope to have them in by next week. Lee

 

My app... 97ss 383ci D1 MM6. SLP shorts and 2 1/2" Y with Mufflex 3 1/2" with Spintech. Lots of back pressure. Modded the 3 1/2" system alot with single 3 1/2" Qtp dump. No back pressure w/ it open 1/2 way or more. The muffler is restrictive for a FI application. Any chambered muffler is to restrictive in my opinion. Straight thru mufflers flow well, but, with more noise. Qtp solves that. B.