Boost issues..

[Swifty1638]

I had not had a mbc on the car, as the one before it seemed to be screwed up. So, Iwas boosting at 10 psi. Today, I got a mini butterfly valve deal from kory, that he had used before. I put it on, and boosted to 18 psi. However, I am not building past like 8 psi in first gear, and it seems as if I had to really step on it to get to the other upper half of psi..not only that, but it would boost up to 10 psi, then pause a bit, then go up towards 15 and lil past. Also, sometimes, when I drive, the turbo spools, but i don't feel that kick in the ass on power. What could be the issue?

-A. Swift