ive just brought a Ba xr8 for 7500 off an old guy, its had growler cai, larger throttle body, twin 2/5 exhaust with high flow cats.. its a 5 speed and im pretty sure its been tuned, im looking to get extractors so first off before i start putting more money into the car there is a medium sounding knock when out of gear and clutch out but when i put the clutch in it goes away... what could it be as this is the first manual ive owned?? and what power could i get out of her roughly with extractors and whats already done? and what kind of extractors would complement a good tune well?

The noise you can hear is most probably your spigot bearing on its way out............

how much is that to repace?

the bearing costs F**k all.

you have to remove the box however.

once the box is out you may as well check & possibly replace the clutch.

see if the flywheel needs machining as well.

nice, cheers heaps guys!

That noise is gearbox rollover, alot of 5 -6 speeds get it once the clutch has been replaced. it is normal, can be annoying though and it goes away when clutch is pushed in.