[Joseph]

Have an 03 GT with a K&N Performance kit (p#57-1531) designed for the 03-05 Turbo. However, when accelerating, the engine bay is very noisy making loud sucking sounds and when I let off the gas the turbo starts to sound like it is cavitating (rapid formation & collapse of vapor pockets…of very low pressure often causing damage to propellers…dictionary discription). Overall its' not a pleasent sound you'd like to hear from a performance engine. I'm concerned enough that I'm thinking of pulling it and replacing with stock box and the smaller K&N filter. I have a 3" catback exhaust that splits into duel outlets but I haven't done anything to the exhaust manifold, downpipe or cat. they are all stock.
PS - I don't think I got any hp improvment with the addition of this filter!!
Any thoughts?? (my 1st post)