Tuning fuel is more to be safe then to make power. The difference between 10.5 and 11.5 AFR's really is so marginal power wise. But being to rich and getting spark blow out on the other hand can destroy your power.

and saying your near the limits of the stock fuel isn't exactly true, yes you may me near the limits of the fuel the ECU or your tuner has provided. But I highly doubt your at the limits of your injectors Duty Cycle or your Pumps flow capacity. If you can run a 150+ wet shot, then thats proof alone the fuel pump can keep up to the bolt on parts you listed flow wise. As far as injectors I really havent seen much posted, nor have i hunted around to see if anyone has had the ability to monitor Injector pulse with or micro sec/bit.