Now we get to the crux, thanks for the input and experience DiRTgarage
I think we are saying mostly the same thing here, but maybe a difference on what acceptable lag is.
1. The GTRS are slower to spool up than the 2530's (you just said that above)
2. The 2530's are slower to spool up than the GTSS (see rb26 forced induction thread)
3. Changing/modifying the head and particularly cams can lower the RPM where the turbo's become effective
The original question of the op is the difference between the GTRS and the GTSS, a huge difference you have to agree. With cams or an increase in capacity the turbo's can spool up sooner, what ever turbo's they are. GTRS for maximum power, drag racing and lagier. GTSS for everyday driving and track work, more response.
From my perspective, I do not consider with all that head work etc and the turbo's coming on full at 5000rpm to be acceptable, I would be looking for 3500 to 4000rpm. With no work done to my engine the turbo's come on strong at lower RPM and with lower PSI. If I could lower my RPM where the turbo's come on that would make me much happier. Cams can only go so far, increasing capacity seems to be the next logical step.
I never say I know a lot but I do read, so has this forum led me to the wrong conclusions above? Everything being the same, would increasing capacity lower the point that the turbo's make power?