Lunati Voo Doo Cam.

Got a A833 with 3.23 rear gears as I live in the country & half my driving is doing 65 mp/h. I know the 3.23's are letting me down. Rear tyres are 255/60/15's.

That cam will NOT like the 3.23's with a 27" tall tire. I drove my car with 2.94's for a bit, it was not a good combination. There's a reason Lunati recommends 3.73's for that cam.

Unless you're planning on installing an overdrive transmission you might want to seriously consider the next cam down, the 10200703. It will be a lot happier with a set of 3.23's or 3.55's, and if you're spending half your time at 65 mph or above you probably won't want to go much lower than 3.55's.