I have a straight cut synchro Quaife F20 box. The ratio's are much closer so it stays in the power band, downside is on a motorway crusing at about 70mph your doing 4500rpm!!

A standard F20 box will loose about 25% of engine power through the transmission, where the straightcut only looses about 15%. When you have a 200bhp engine this 10% is alot to gain.

As a daily drive dont even consider it. I now drive with ear plugs as the noise from the straight cut gears.

As for cost the gear kit alone was about ?1500 + vat then you need some machineing inside the box, then put it all together. Total cost about 2-2500k!

Martin