What would be better, run a small pulley and shift sooner or a slightly larger pulley and shift later, assuming both setups would be near max impeller speed?

On my 355/f1a combo I run a 7.65 crank pulley and a 3.40 drive pulley. Max impeller speed is reached at roughly 6200 rpm and I see about 18psi when shifting at 6100 rpm.

Would it be beneficial, for instance, to run a 3.70 drive pulley and shift around 6600 while max impeller speed is roughly 6750 rpm?

Would this maybe give me a longer powerband?

On a side note, how bad is it to overspin a centrifugal?

 

With the size of that F1A I would rev it higher since its already going to be hard not to have belt slippage. I never see anyone over rev a procharger, but guys use to do it all the time with the Vortech blowers. By reving it higher the boost will come in later in the powerband, which would probably be a good thing since its already making crazy power. Plus boost to early would make that thing hard to hook.

My setup I have a maxed reved D1SC at 6200, keeping the powerband narrow and a alot of TQ down low (boost coming in earlier).

 

Well the tune isn't perfect yet by any means, but at the moment it feels like a Supra like powerband lol! Amazingly belt slip isn't a problem, but traction is. It pulls pretty crazy in the upper rpms and my worn out drag radials dont like to hold on much.
I'm in the process of building a new fuel system now so I guess i'll tinker with it when I got all that done.

 

A turbo would help...

 

I try to match the impeller max rpm with the basic rpm of the cam. Running a D1 383 and a CamMotion cam. @ 6500 rpm the D1 impellar is approx 65000 rpm with a 7.6 --> 3.4" pd ratio. The D1 has a 4.44:1 step-up gear increase. B.