There are many HPOP options nowadays.
Diesel site sells a upgraded pump called the Adrenalin, and seems to be having good results. They also make an the Overdrive unit which basically bolts to the front of the HPOP and turns it tad bit faster.
There are Stealth pumps available from Stecher Performance, these pumps come in a few different flavors from mild to wild and can be upgraded in the future if you needs change. They are VERY nice pieces but come at a cost.
Other that changing HPOP's you can switch to a Hybrid injector which uses less oil than the stock split shot will. Hybrid also come in many different flavors, and you will see a sizable increase in HP's. You can run these injectors with a stock HPOP that is in good condition.
I think what ever you choose the price will be roughly the same.....IIRC.
