You will hear the plumb back if you listen carefully even with a stock air filter. After market BOV's may hold more boost most of them come with adjustable spring tensions.
Another thing to note is that the GCG quote of $1900 for the hi-flow is just that, a quote. I have heard people on this site claiming that they got it done for figures around $1300...
You might want to give em a call and see what they say.
had the same thing happen to me. You can get a noise filter which might cut some of the alternator sounds out, but the is due to a blown resistor in the head deck. If you take it to your local car audio place they should be able to fix it.
Too Hot, tell me about it. This heat is making me so tired. I guess we shouldn't complain though, as soon as winter comes back to the ACT we will all be wishing for weather like this.
I say suck it up while you can...
If you want the pppsssshhh sound just install a pod filter. Some are quiet loud and they wont cause your car to stall & back fire... (Make sure you get some sort of cold air box with it though...)
GT28 is a great turb for a r33. But dont bother putting it in until you have a new FMIC, aftermarket engine management, bigger fuel pump, fuel pressure regulator, heavy duty clutch etc etc.