4000-7000?
 

1990, stock 1.6, track only. 6spd/4.1. 7000rpm max. FM manifold/downpipe/open exhaust. 30 min. sessions, some W2W. Tuned to 220 wtq. or less.
Tracks are low/medium speed. Would not be hitting 6th on any of them with 4.1. The 6 spd. keeps 4000-4200 as the lowest RPM point everywhere.

Have GT2860RS, (.64 A.R). Considering GT2560R, same A/R. The 2860 feels lethargic 4-5K, and the torque spike at 5K feels great but causes corner exit issues.

I know the smaller 2560 will give a more driveable torque curve at mid-range. The question is it "too small" for a track car, in terms of compressor efficiency etc.