You can get a custom set of headers for $1,500. A supercharger kit for a 560 SEC starts at $1,500. Boost and hp are dependant on you and what additional power adders you go with on your kit. You will need to buy your own Procharger P1SC.

At 7 psi my car dynoed at 346 RWHP and 404 RWTQ with no intercooler but I did have a methanol/water injection kit. I'm having some custom pulleys made, cog and 8 rib, now that should take me to around 10 to 14 psi and well over 400 RWHP not to mention that I'm now running a large air to air intercooler.