Yeah, typically the "backpressure" from the air sitting in the exhaust it is enough for it to spool up. Guys are using up to 5" systems and not having any problems with spool up. I wouldn't worry about that....just worry about your tranny when you start adding power with electronics. 
__________________ 2004 GMC 2500HD D/A CC Carbon Metallic w/ LB7
4" turbo back MBRP exhaust, Cognito UCAs & HD tierods
TST Powermax Programmer, Diablosport Predator
285/75-16 BFG T/A KOs, Eagle Alloys Series 187
Clifford 2 way remote start, High Idle, Bilstein 5100s, 1.5" lift blocks
AFE Magnum Force Stage 2 Proguard 7 intake Waiting install:Rancho Steering stabilizer....all thanks to NorCal Truck  Support your Supporting Vendors |