01ITR#700

I've been doing custom exhausts and downpipes on a few different vehicles lately and wanted to check with you guys and get some info. Mainly, is it advantagous on a turbo Honda/Acura to run a 2.5" mandrel DP and then flare it to a 3" cat and 3" mandrel bent from there back? I've done two Turbo GSR's in this configuration as well as a Talon TSi and all 3 gained 1-2psi from the better flow and gained a MUCH faster spool up. Would running a 2.5" Turbo back yield much less gains over the 2.5" DP to 3" cat and 3" cat-back?
Thanks for any input.
Mark


[Modified by 01ITR#700, 9:11 AM 11/26/2002]