I had it with a lethal after cat x pipe, droned so bad I added dynomax race bullets as resonators, still droned terribly. I took it off and went with a GT500 axleback. I think that the rtr is better suited for a car with the factory resonator in place.
Livernois sells the kit with the insert already removed called the severe windstorm. However, don't bother asking them about the maf size, they require you to purchase thier tuner and tuning. Yes, after spending the $442.87 (including shipping) they basically tell you to hump a stump on the maf...
I made 398 and 382 and ran 12.1 at 113 on a 93 JDM tune and ran 11.88 at 116 on my POPS Racing 93 tune. Haven't had the pops tune on the dyno, but I'm very happy with it and with Adam Marrer.