Personally I would have gone for stage 3 provided you have a decent HG, at the moment you are getting no gain with the T34, it's only used to provide boost the the T3, I would upgrade the injectors and MAP sensor and maybe if you asked MSD kindly they would rewrite your calibration?

T34 isn't exactly laggy, it would be slightly more so than the T3, it dosen't matter what stage it's at to run it is, it's how it's driven which will run it in. I stayed off boost when running mine in and gave it little bursts every now and then.

Martin