300-370 hp budget (flywheel hp)

Top end kit. But honestly, a Vortech v3sci really fits the bill.

Cheapest option would be finding used parts in good (useable) condition. Would need heads, intake and cam. I would do roller rockers and 1-5/8 headers and 2.5" exhaust (catted will be fine if your area requires them).

All kinds of H/C/I combos but I will just talk to my combo which is in the 320-350 range. Stock short block, 3-bar GT40s (intake and exhaust ports have been smoothed),as cast Explorer EGR intakes, 70mm TB and EGR (still running EGR), C&L 76mm MAF and 24 lb injectors, 1.7RR, Crower 15512 cam, MAC equal length headers, MAC 2.5" ProChamber with aftermarket cats added, 2.5" MAC ProDumps with Flowmaster tailpipes. I have a 3G alt and Contour e-fans (some tests have shown 15-20hp by removing the clutch fan). My entire setup I scrounged used at a total of about $1600 and a little horse trading (e-cam for Flowmaster tails).

Good luck with the hunt.