Eh...I don't understand wastegates and blowoff valves...

[GT40FIED]

Originally posted by AzCivic
wastegate vents exhaust gases at the turbo so the turbo doesnt make more boost than you want, say you want 12psi, it'll open once the turbo makes more than 12psi.

a BOV situated inbetween the turbo and throttle body vents pressure inbetween shifts(when the throttle plate closes) so the air doesnt go right back into the turbo and screw something up.

Exactly...shutting the throttle down under boost too quickly will cause a pressure surge and possibly damage the impeller, bearings, or create enough to pressure to cause the turbo to overheat which causes the oil to coke up and the turbo to fail. As for the T-xx...it's a reference to the housing size. A T-66 = 66mm housing. A T-100 = 100mm housing (you could just about fit your head in one of those). You get the picture.