i just recently got an invidia dp installed on my 03 wrx and my car has been trippin. the only mods i have are dp and hks carbon ti exhaust, turbo xs rfl type h bov. when you floor the gas the car seems to drive fine till it reaches about 5 rpms then the boost starts wavering back and forth and a weird stuttering or rattling noise seems to be coming from the engine or bov..... i checked around and found nothing wrong. i understand that the bov sucks and i tried tuning it and even replacing it with the stock bov but the problem still exists..... please help

 

check your gasket from the downpipe. did u use a new one or the old gasket.
get one other person in your garage. put soap (without water is better) on the flange. have your friend rev by blipping the throttle (dont hold it down) and you look under the car for bubbles. do this fast so the soap wont evaporate. if it is the gasket there then get a new one and install it. trick to install then without leaks is after u install let the car warm up completely then torque the bolts again.
if its not the gasket then u have a leak somewhere else.