how hard is it to change your waterpump by yourself...

 

It's a straight forward job. Just be sure to drain the coolant from the block as well as the radiator otherwise you'll get your opti wet. Use teflon sealant on the waterpump bolts when you reinstall them. Also make sure you transfer the drive coupler from the old one to the new one.

 

or upgrade to an electric unit, more HP at close to the same cost of stock replacment...

http://www.projecttransam.com/projects9.asp