I wouldnt bother with a chip to be honest - the cost involved (from what Ive heard) doesnt warrant the power gains from one.
Best thing: either visit www.jimmockmotorsport.com
and look at the DEV kits (different packages with approximate and apparently fairly accurate power gains).
Probably the best thing to do though is simply upgrade the cam - shouldnt cost more than about $800 fitted (and maybe change the air filter setup)
Alternative, cheaper cams are wade cams or crow cams - not sure on the power gains from these, but they are likely to be just as good as the jim mock ones!