contrair mofrair.i have a lot of experience with the noises .....i have a stock 2000 psd and put an 18k diffuser box in..... basically a trick that tells the injectors to flow 150% at 100% throttle or to flow 50% at 10% throttle etc.,no real noticeable difference.then removed red vac hose from turbo! boom lots of extra balls and neat noises.1st noise is under load.light p phishhhhhphish phish.determined that the turbo is still spooling but as truck shifts the extra boost that magically appeared when the fuel pressure went up is simply no longer going in the right direction .or spitting out around the wheel.i dont see a problem with this.after these simple mods i built a nice big unrestrictive filter set up and took the turbo off to see how i could get more boost.dtermined that exhaust valve needed to be a lot harder to open.fixed accordingly and reinstalled.then started messing with the resisters in the dfuser box.(bypassing different ones and fount a setting that with the added boost and huge increase in fuel delivery will cook the rear tires on my dually while completely blocking out all rear vision.....very kool. but with the good comes the bad and surge kicked in in a bad way.basically had to put a throttle switch activator on the module cause if it stayed on once the pedal was released it wouldnt rev down.just sat there and chattered at about 2800 rpm.this is surge and is not good .cutting the module immediately when you let off the gas helps surge dissipate rapidly.now the really bad sound .if truck is goosed from 0 to about 30 or so then released from wot i get the whoosh and pphishh and belt squeeling sound all at once.popped hood/took off intake boot to turbo/punched it real quick then released throttle at high power setting and in about 2 seconds went from idle to 3200 rpm /boost pegged almost immediately then upon throttle release turbo fan immediatly and violently stopped and went in reversedue to the massive pressure build up slamming back out the intake.very bad but can be dealt with by simply not instantly releasing the throttle just to hear the kool noises it makes.......
disclaimer.these mods (by my estimate ) are puttin at least 150 hp to the ground on my truck but are not endorsed or recommended by me for use by anyone who pays someone else to work on their truck as they are as cheap and effective aas they are destructive.
so if you hear the belt slip sound when you let off .you have gone too far with the redneck engeneering and need to back it up and do it right.
on the other hand if you love a greasy night under your rig then have at it and ill help if i can................