Ive got the magnaflow x-pipe with high flow cats and the 3" catback with magnapacks and its great with my procharger
They recommended it only for S/C aplications.
thats what magnaflow told me as well, i drove it without the s/c for a short while and i didnt notice that much in a loss but i did gain hp. Weapon-R Intake Magnaflow catted x-pipe and no tune got me 291rwhp. Altough now with the s/c it great!