i have a t-25 HMT on my 90 civic si. runs great but when i get on it i reach a max boost of 3 psi and then at about 4000 rpms i begin to hear a fluttering sound. whats making the sound? the turbo is from a 98 eclipse so the wastegate should not be opening? maybe BOV leak? anyone help?

 

Well, how did you setup your wastegate? Are you using the threaded spacer, carb spring, or are you using just the stock setup?
Also, how did you setup your oil return on that t25? Do you think you could post or send me a pic of it? Thanks

 

make sure your wastegate is hooked up properly, boost line and vaccum line. also if your exhaust pipe and muffler isnt letting the air flow out fast enough, that also can take a part of your turbo not spinning fast enough.

on my turbo setup, i had 8psi with high flow muffler *ones off ebay* with 2.5" piping from cat, but when i removed my muffler and put a stock muffler to be silent *stupid neighbors* then it only reached 4psi! so the exhaust flow played a part in mine.

 

fluttering sound.. sounds familiar ... check your charge pipes..there maybe one getting loose when you begin to boost