The sound you hear when letting off the throttle is the wastegate valve blowing open and then closing. I know what you mean, the first time I heard mine , I was like is it suppose to sound like that.. Found out later it was normal.
I'm use to hearing the clean sounding blow off valve that you usually associate with turbos.

 

Do you have a boost gauge installed yet? Be sure to check it. When I first installed mine it was boosting to 8-9lbs on stock injectors running dangerously lean and I didn't know it. Guess I was lucking. Had to trim the wastegate spring down until I was right at 5lbs. It took several trimmings to get it just right. You might also want to check your 02's under wot to see if they stabalize. I was told they need to be above 900mv.
Mine was falling into the low 800's even at just 5lbs. So I'm the process of upgrading to larger injectors.

 

are any of you guys with this kit running a bov. i think that sound is the back pressure of the turbo returning and trying to push it the other way. personally i think if you run that with a bov for a long time you may ruin your turbo compressor from to much air trying to blow back on it after a full throttle run then letting of.

 

No boost gauge yet, wish one was included, the kit costs enough to cover even a cheapo gauge for safety in my opinion. I have off today, called in sick not feeling well enough for work, but good enough for some driving and info gathering on this. Might try to get an exhaust shop to weld up my turbo inlet pipe today. Have to find a good one though, not some kid who don't know how to weld or some old fart who can't either...lol.

 

Yea you need to fix those leaks. I have a small exhaust manifold leak and it killing boost.

 

Is a bov some type of boost controller? I don't know all the turbo lingo yet.

 

no thats the peice that goes btween the turbo and the intake. it blows off the air pressure comming from the turbo to the intake when the throttle plate shuts. it keeps the boost going into your intake from returning to your turbo and trying to spin it the other way. that despools your turbo when you let off the throttle which can be bad in the long run it causes alot of stress on your fin on your compressor side of the turbo. and bov is blow off valve.

 

Well I'm getting the leak welded tommorow night by a local guy, seems pretty cool. Small shop, does mostly hot-rod stuff, has an exhaust bender and may be able to make me a tailpipe so the sound goes out instead of resonating under the bed. Since my bed cover got stolen a few weeks ago the sound is pretty intense, at least compared to a stock exhaust. The wastegate sounds are pretty loud too. Maybe it worse because I have a standard cab and don't have as much distance between me and the turbo to muffle the sound. And the SES is the P1336 crankshaft position [CKP] variation not learned. Hopefullt I can get that fixed today. I also looked at the data with a predator diagnostic tool in the (DTC not ran scc) section and saw this....DTC not ran 1 of 9m, bank 1 efficency below threshold. What the hell does that mean?? Is one of the O2 sensors going bad or is it bad already? Other things I was monitoring were MAP,IAT,O2 readings in mv,The MAP should be running at what with a TURBO??? I'm getting about 14-15 psi when on the gas hard??? I hope its not boosting that high????
Well I gotta eat lunch so more a little later. This thing is gonna fly when I get these bugs out!!

 

Exactamundo, Hefdaddy. I was also turbo lingo illiterate, did a crash course. The chatter sounds really cool but is hard on the compressor turbine in the long run and will slow down the turbine if you go open-close-open in quick succession. Usually vital for manual trannies and optional on autos.
Don't totally trust the MAP for readings but do try to locate your boost gauge in or very near the intake manifold. Gets a better reading if there is intake pressure drop inside the manifold vs pre-TB.
Find a wideband O2 in the area and get it checked out pronto. Too lean, above 12:1 A/F is not good long term.
Enjoy, they are fun!

 

Looks like I need some new toys to sort all this stuff out. Where do I get a wideband and how much does it cost?