Only 4-5 degrees timing at peak torque? What kind of fuel are you running, pump gas? With E85 I can run 22 degrees timing on 18psi so around 1.20 bar. I plan on running 1.6 bar with around 20-22 degrees timing with E85...Crank that timing up if you have good enough fuel.
is the 1.2bar on a Garrett3076/HKS3037??? its a big turbo so there is a huge difference in air flow at 1.6 Vs 1.2.
mine timing was on uk super unleaded (~98 octane). So Running E85 you can run more ignition but i wouldn't have thought 22 degrees would be manageable on a 3076 at peak torque. Is your base timing 100% correct? was ur car road tuned or dyno? with e85 you can go past mbt and not knock so if your running a true 22deg then it might be worth checking power at lower timing
Even with a 28rs and 2871 i would only be aiming for ~10-14deg at peak torque for anything over 1.2bar on 98 octane fuel.