i don't know the compression on the d15b but for boost, lower is better in the sense that its safer.

either way its mostly in the tuning. dont' cheap out on the fuel management. i'd go with uberdata dyno tuned by professional tuners or if your into that thing tune'd yourself with a wideband,egt and datalogging. uber is still cheap yet very effective. and pairing it with some cheap dsm 450's injectors, and maybe a new pump and fpr for added insurance you'd be good to go.

like b16ahybrid said, shoot for around 200whp for a daily driven car. too much more and beating on it daily and eventually the rods will start to give way. if you have the time and money, get the new d block on a stand and swap in new pistons and rods. you'll be much happier than if you had to take the whole thing out down the road to fix/replace the bottom end.

i just installed my hmt kit on my y7/y8 mini-me so if you need help pickin out parts or what not lemme know.

-Luke