T-25 Boost Levels

[GSXDNA]

I have a '99 GSX 5spd, totally stock except for a 1G BOV and a boost gauge. I have had 2 other turbocharged mistu's in the past...a 2G GST and an Evo VIII. Both cars had stock turbos and MBCs. I noticed that whenever I would turn the boost up, the amount of boost drop off I would notice stayed the same. For instance, if I was running 15 psi, it would drop to 12 psi by redline. If I was running 20 psi, it would drop to 17psi by redline.

Likewise, with my GSX I am running stock boost (hitting 12psi) and experiencing a drop off to 9psi by redline. I've done a lot of searching, and I see that most people say that the stock T25 just can't hold 12psi to redline. However, I can't help but feel like there is something else cutting the boost back as the RPMs increase...maybe the wastegate actuator? Anyone have any thoughts on this?

 

[tbonitz301]

I would make sure you MBC is working properly. my 95 gst is set at 16psi, and drops to about 12psi at redline.

 

[2GAWD4U2NV]

I have my MBC set to spike at 17psi, hold 15psi until it's close to red line, but once it close to red line it falls anywhere down to 9-12psi depending on weather/operating temperature. So I don't believe you are experiencing any problems. It's just the good ol' T-25.