Supercharger

Pistons, rings, head gaskets, switch to EFI with a programmable engine management computer. Then you will have a reliable engine.

 

ASSUMING everything is mechanically in good shape, pretty much every car/engine can handle around 1/3 more HP with no mods to other components. IOW, if you restricted the boost to around 7-8 PSI, you should be fine with no other mods. IMO, for a typical production street car, any more than that can easily put you into a never ending loop of "upgrades" or repair. I have installed turbochargers on several street cars in the past and one of them managed 15 PSI of boost with no mods BUT it was a FWD car so it couldn't get the kind of traction that would put enough strain on the rest of the drivetrain to matter! Basically, the lack of serious traction was the "safety valve." But on RWD cars, 7-8 PSI worked great - a decent HP increase with no other issues.

For example - first thing that usually gets replaced with engine output above around 30% is the clutch because it slips. Great...now the clutch doesn't slip but the tires spin too easily. OK, stickier tires. Now the clutch doesn't slip and tires stick but the axles can't take the added torque and break. Better axles...now the differential/transaxle gears can't take the torque so they break. The previous could happen in reverse order - diff/transaxle breaks first then the axles. But, either way, on it goes...

I seriously considered the 928 supercharger back around '10, planning on the 7-8 PSI. The 928 cost around 6k USD then - don't know about the price now or even if it's available - but the year I was planning to do it, the IRS informed me that they needed my money more than I did. Afterwards, other things came up money-wise for a few years that prevented the purchase and now I have to admit that I pretty much lost interest and just prefer to keep the car stock. TBH, nowadays I'd probably appreciate power steering (and better air conditioning) more than increased engine power! Sad but true!

 

I was running 22-24 psi for a couple years without issue, 600-650 crank hp. Valve springs and clutch were up graded, efi added. The build is on this sight somewhere if you search.