i wouldnt say a log manifold would really hurt your setup, log manifoldswill definitly be better for spool, and for more of a streetable setup.
i too am running a log manifold and dont really feel that it holds my setup back at all, im on a GT2871R and just got my car tuned and made 300whp@10lbs and i just upped the boost to 17lbs, around 400whp now, getting it redynoed/tuned.