There is no Rev Limiter on a stock shee, I think you mean the TORS, or throttle override, that's not a rev limiter.
Yes, a +4 timing will help ANY motor, but it will compliment a motor with opened up air intake (better filter, no lid, etc.) and with pipes much better.
Three very cheap and easy mods once you have your bike piped, air filter and jetted are shaving the flywheel, bumping your timing and shaving the head. Noticeable and very, VERY cheap....