Should of gone a split dump + front pipe.. wud of flowed alot better. Dyno tuning will do nothing for ur psi, thats ur boost controller and im guessin you dont have one? If you have a bleeder (as most boost controllers do) they tend to drop boost off towards the top end anyhow, nothing new nothing to worry about! Not sure if u have a cat-back, if not get one and you should run around 13psi without a boost controller (that comes bak down to around 10psi)