September 12, 2003Ok here is my comparison of a 40 Series Delta-Flow Flowmaster and Pro-Street Spin Tech. My setup is 5.7 vortec, Airraid, Wester's PCM. I first used a Gibson Cat-back and bolted that up for about 6 months, was way too mellow and quiet (my mom's factory exhaust on her Northstar Caddy was as loud as my gibson). So I unbolted the Gibson muffler and left the 3" flange and just bolted a 3" Flowmaster up and had a turn-down dump right before the rear axle. Was good and loud but after a year, It seemed to get quieter (or i got used to it). So i just unbolted the 40 Series and bolted the Pro-Street up in place. WOW, Spin-tech is much louder and deeper. Alot louder interior also, but if you are looking for the loudest deepest sound, the Spin Tech Pro-Street is the way to go. If you want a true hot rod sound go spin tech, if you want loud and still keep the family happy go flowmaster.
If any one is interested I have a 3" single center in center out flowmaster 40 series delta flow, only a year old....make me a offer