I went with the delta 40s because they are supposed to sound the same outside the car, but cut down on resonation and noise inside. Its pretty loud at times, but not obnoxiously so. Flowmasters are pretty unrestrictive as far as mufflers go. Probably won't see big number differences. The cutouts are big time cop magnets. I did them less for power and more to set off car alarms. I uncapped them yesterday for a car show and it went over pretty good. I did not get a kit because they don't make one. Flowmaster does make an over the axle pipe(from mufflers to out the back). I brought my exhaust guy the mufflers, the over the axle pipes(they are mandrel bent) and the cutouts. he custom fit the over the axle pipes and everything else. It would not have hung right with the over the axle pipe as it came, but he said they would flow better than the ones he could make out of raw material. I used those $27 ones from summitt on the car. Worked and made fine. Believe it or not the wing nuts don't come loose as long as you tighten them a little with a cresent wrench!:s5