I had thought to put an RX-8 engine and 6-speed sequential in my Sport 190 Series 1 car, but looks to be quite difficult.
I'm a big fan of RX-7 engine in the Standard Formula Mazda (derived (copied) from the Russell Racing Formula car (before they switched to current F3 based car)) and the RX-8 engine used the in the Pro Formula Mazda currently used in the Star Mazda Series.
The Official Star Mazda Championship presented by Goodyear Website
Star Race Cars Web Catalog
The Official World Speed Motorsports Website
The RX-7 engine is bullet proof in the Standard Formula Mazda, mainly in that it doesn't blow up if you over-rev, so a great choice for an affordable school car as Russell used have to have figured out before the insane switch to F3 based school car and a turbo engine from the Evo. Competitive racers get about 2 seasons out of the sealed engine in the Standard Formula Mazda.
The sealed RX-8 based engine in the Pro Formula Mazda has been less reliable, despite the upgrades to fuel injection over carburated, Motec ECU over mechanical distributor and ESD ignition. Seems the main reason for poor engine reliability with the Pro Formula Mazda is the choice to not allowed closed loop lamda control, so easy to lean it out - driver controls the MAP setting, driver is the "knock sensor", and lean is fast. Too tempting.
I much enjoyed racing the two types of Mazda Formula cars in Russell, Rototary Rockets, SCCA, and Star Mazda. But I bought an Exige S in '07, started tracking that, started running it in Lotus Challenge Series and CFRA in '08 and sold my Pro Formula Mazda this year.
I bought a S1 Sport 190 last year and thought about an engine / tranny swap from the Pro Formula Mazda - so RX-8 engine and 6-speed sequential. But measuring it out, was too long by about 3 feet. Could take out about a foot by relocating the dry sump, but can't take out much more, so would need to extend the wheel base of the S1. Looked for alternate sequential, but didn't find anything shorter that could handle the power.
Also didn't get a straight answer from Red Line Time Attack if the Sport 190 would be allowed in that series. So instead I'm focused on continued development of my street legal Exige that runs in Cup Class in Lotus Challenge Series.