A great upgrade is the bosch 040 or the 019. They are rated at 600 odd hp and are a near bolt in fit to the standard intank arangement (only need a hacksaw and a big hoseclamp).
It will only take a complete novice 1 hour to change it over too !!
The bosch 044 is rated at 700 hp, takes a lot more to fit (its designed to be an external pump, and is nearly twice the cost. shop around for the pump price, the prices will vary by hundreds 1! dont get bent over ! good luck