Over the last few weeks i've noticed full boost has creaped up the rev range abit, (My99 STI ver 5 by the way), used to get full boost around 3000 rpm, now its around 3500-4000 rpm, I have also noticed a slight blowing from the front of the car but cant quite locate it. Guess i really need the car on the ramps to see where the problem lies...

I've checked/cleaned the normal things, so is the above likely to be the problem?...

Thanks in advance...

 

Yes, (depending on how bad) a leak in the headers will delay the time taken for the turbo to spool up hence boost coming in higher up the rev range