It's a '05, When I first installed the Defi boost gauge, it would pike to 1.6bars, drop down to 1.5, then after about 5k rpm, it would drop to like 1.3 bars, I was wondering since now I have the Hallman MBC with Buschur Racing Mass Air Pipe, and filter, after installing the MBC, i maxed it out at around 1.3 bar, is it safe to 1.5 bars?

Also I would need to run the heavy spring now, and is there a way I can make it hold boost at 1.5 throw out high rpms?, thanks.