Sounds most like a boost leak to me... a small one, hence the whistle/groan/woot sound.

I wouldn't run that filter. Gets plenty of poor reviews, a couple show-downs have shown it to perform very poorly and I've seen enough of them collapsed with bits (of just the foam) sucked into the turbo for me to go nowhere near it. But, if you like it that's fine.

Great....a small one is going to be hard to find.

That's the filter that was on the car when I bought it. I had never heard anything bad about it, so i always used it. But that makes sense that the "sponge" would fall apart and get ingested by the turbo. Might be time for a change, especially if its gonna save my turbo and add a few horses. I'm thinking just a cone w/ paper filter.... seems to be popular. Anyone know of a good one? Might be time to start a new thread :)

Google "diy boost leak tester". ;)

Google "air filter show down". ;)

Searc h on the forum for cold air intake threads or CAI or best filter... and so on. The two most popular options (and the two which typically come out on top in tests) are AEM DryFlow and Apex'i. Amsoil's air filter's are supposed to rank right up there with those other two but they as well as the Apex'i command a premium over AEM. I like the AEM for price and performance.

Whatever you get don't just leave it sucking in hot air from the engine bay, you're better off just keeping the stock box and putting in a GOOD air filter.

4/6 psi at wot.. not on deceleration? does compression surge only happen when the throttle place closes?

Apologies for bringing back an old thread. But I resolved the problem and if anyone else has the problems listed above, hopefully this helps.

As i posted previously, my boost was cutting out at wot and I got error code 34. I replaced my stock BOV, with the Bosch and after checking every intake hose and cupler, I found no holes, cracks, or loose fittings. Since that did not fix my problem. So I went to the next suggestion, which was the wastegate actuator. After inspecting the actuator (opening up the canister) I found a small hole/crack in the rubber diaphragm. I bought a new "CT26 Wastegate Actuator" from driftmotion (which was a direct fit) and installed it. Went with the 11 psi since it was the same price as the 8 psi. Anyway....Problem solved!! No longer cuts out at wot and is able to boost to well over 5 psi (which is were it usually cut out) no more error codes, and woot/hoot sound went away.

cre - thanks for all your input. You'll be happy to know that i ditched that sponge filter and i'm currently running apexi's cone intake filter.

I've been having the very same problem... but have yet to check the actuator... hopefully all this info will come in handy. Ive had nothing but trouble with the turbo on this car since I bought it. Some days it would run fine, but most days its awful... most recently my ebc stopped working... when I flip the switch on it does nothing. My factory boost gauge is still hooked up and working, does this make any sense?
this is my second 89 with the 7m gte ...im starting to regret it!