I have a 99 si with a b18a1 out of an LS Integra. It has the GReddy 18g si turbo kit. My problem is that, without a boost controller, it spikes at only about 12 psi of boost at 5000 rpm and then falls off to around 8 or 9 psi after 6000 rpm. I know this turbo can make more boost and the car can make more power. Is there something that could be wrong with the internal wastegate setup?? I have read that there are guys in this forum running 17+ psi with this turbo. If I hook up the profec b, on high boost, the turbo only makes about 11 psi under full throttle. The turbo does not spike as bad with the boost controller hooked up. The motor is built failry well so I am not worried about it taking up to 15psi. Much after that and I worry because I did not put it together, but just a little more would be nice. Any knowledge would be greatly appreciated.

 

The problem is the wastegate Flapper and door, for they are only about 32mm in diameter. The wastagate actuator is rather small and needs to also be adjusted. on the 18G (using a T2 Exhaust housing and flanging system) you're not going to get much more than 300whp, and that's with the porting of those items I listed above plus the downpipe adapter. Only a carbide bit can properly port these areas.