While superchargers make big power down low.... don't forget if you pulley them aggressively you can see a few bad things: belt slip and namely heat soak,
As others have suggested buy a used CTSv blower (ctsvowners.com) and plop some LSA/LS9 heads on your shortblock with appropriate cam and it will make 650rwhp and drive great. Their main downfall is heat soak though.... so if you do back to back passes or plan to road race it.... it will not run cool. A large reservoir helps.... but that will only prolong the heat soak.
The centrifugal blowers suffer from less heat soak.....
I haven't seen ANY E-Force blowers make big numbers on the dyno.... and not at the track either. A stock CTSv blower, stock heads, smaller pulley, cam/headers, e85/inj will run 10's all day long with a manual trans.... low 10's with an auto or faster.
Turbo's work too
Boost by gear is a wonderful thing:
My other RX-7.... running a 100% stock T56 Magnum and McLeod twin disc.
https://www.youtube.com/watch?v=y472n4EbWO0
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Project: 1969 Chevelle, alum 5.3, GTS76 turbo, Chiseled Perf A/W intercooler, Holley Dominator EFI, Davis TC, JRi coilovers, 14" brakes, T56 Magnum. CTS-V Recaro seats!
Coffey Fabrication Nashville, TN doing the fabwork! 800rwhp+/25mpg+/9's@150mph goal
https://lateral-g.net/forums/showthread.php4?t=52976
1993 Mazda FD RX-7, built LS7, T56 Magnum, Holley HP, Davis Tech TC, 8.8" 3.73 Cobra IRS diff, DSS axles, Ohlins coilovers, big brakes.
CCW 18x11 front 315/30/18's and 18x12.5 rear on 335/30/18 RA1's,
2850lbs
10.31@137mph 165mph Shift-Sector 1/2 mile speed
441ci AllPro headed motor and 200lb weigh reduction in the works....