Ive been test driving the car and noticed a pool of oil underneath. Inititally I thought it was power steering as i'd been making a lot of changes there but on closer inspection I found a pool of oil on the gearbox - uh oh!
It turns out i'd installed the driver's side gearbox oil seal completely wrong and it had been chewed up by the intermediate driveshaft
it SHOULD look like this (after installing a new one, this time installed flush with a seal driver)
Topped up the gearbox oil and so far so good (or more like refilled... it had lost over a litre which could've ended badly. At least I found it after only doing about 30 miles in the car)
It's going on the dyno on Monday ... fingers crossed there's no more issues and it makes good numbers!