I'll help you out a ton. Below are the part numbers and mod names of what I did on my 2008 and my 2010 STA V8.
I did the below mods twice and I did them in different combinations and in stages. I wouldn't waste my money on anything else. These are tried and true.
I did:
Steeda Underdrive Pulley Kit 701-0005A
Zabteck Modified Throttle Body V8 4.6L
SOS Ignition Coil Set 31850 (didn't do a damn thing without increasing the gap)
K&N 57-2573 FIPK
SCT Xcal3 ECM & TCM Tune (87 and 93 Octane) By Torrie @ Unleashed, Strategy JPCH1A5, TPBF0, 9L2P-7J104-AG. PCM Code: SHS7
Magnaflow 14236 Exhaust
DMH E-Cutout (super fun noise maker lol)
Psycareyo 2" Drop Springs (currently not available)
Everything else is pretty expensive. You could do new heads, port or polish, supercharger, STS turbo...all those add serious power but the cost is pretty insane. I had like $9,000 into my STA and I bet Supercharged SVT is closer to $13,000+ in his. While the power is great, the power per dollar ratio is horrible. Even with that extra power, you still have one of the worst shifting 6 speed automatics that Ford has ever made.