Bigcat, thanks for the suggestion. It seems we’re all in uncharted territory with exhaust on the 05+. I'm replacing the H-pipe with a Prochamber, from the other cars I've heard this helps with the rasp and is a little quieter than the o/r h. I've also thought about going with high-flow cats but if they sound anything like the stock h-pipe did the sound below 3000RPMs is OK with bearable drone however when you get above 3000RPMs the system seems to get quite and really doesn't sound much louder than stock. I ran the system for about a week with the stock h-pipe and didn't hate it but wasn't to impressed. I guess the muffler placement on the ’05+ is going to make the sound I want not happen.... but if I could get it to sound close to as good as my '02 GT with an o/r h-pipe and wield-in 40 series flows did I would be happy. I guess my point is I've been driving around with this combo on older body style Mustangs for over 6 years now and have never had to worry about trying to accelerate in to high of a gear due to drone. I read all of Flowmaster's info on these mufflers before I bought them and if there really has been a ton of R&D on these mufflers to eliminate drone I don't see it. This is just my opinion if you guys like yours I'm happy for you, and if the prochamber doesn't help out with my setup there might be a set for sell real cheap.
