Twofaced,
The wastgate mearly controlls the amount of boost that will charge into your engine. 8 psi is NOT he max amount of boost your turbo will spool ( it all depends what kinda size turbo you have) but im guessing its no smaller than a T3... The wastegte just controlls the amount of pressure producedd by the turbo that is then being forced fed into your egine. You can change the amount of boost on the wastegate with what is called boost controller, they make manual (quick an easy install) or an electronic contrroller which can get very complex anquite pricey. So if you wanna raise your boost just get a simple manual contol valve by turbo XS or you can even mke your own!
"It is an external one that connects to the turbo manifold. The exhuast gases from the turbo manifold blows into the turbo and keeps on blowing. The turbo keeps on spinning and spinning and you get more and more boost! But you don't want too much boost or else your engine will blow up! (Too much boost = too much power = pistons can't handle this power = goodbye motor! ).
So how do we regulate the turbo so that it does not overspin? We have a wastegate. The wastegate sees how much boost you have in your engine. If you have it set at 7 PSI, when the wastegate sees 7 PSI, it will open up and send the exhaust gases AWAY from the turbo so the turbo does not keep spinning!
Imagine you have a windmill and you blow on it. It will spin and spin and spin. However, if you put a sponge in front of your mouth, the windmill will slow down. Thats exactly what the wastegate does. It slows down the air flow from the exhaust"