A lot of questions there Mikey, all I can say is if youre seriously looking into it, BB will let you have a drive in one!
Ive had the high boost one out on the road (the one in Max this month) and before I blew it up I was used to a fast Clio when I was making average 14.5 second passes over the 1/4 mile, in mine. So I know whats fast and whats FAST if you get me. The BB turbo was was running around 240bhp (they have their own rollers which are pretty accurate IMHO) when I drove it and I wasted a Saph Cossie on a short stretch of dual carriageway like it was standing still. And the Cos was caning a long line of normal traffic at warp speed already. Now admittedly it was only a Saph, but it was modded and fast.
Theres no timing for it yet because its not been out and quarter miled properly, so any claim wouldnt have the ticket to back it up. But as Steve says, you can make some rough calculations bearing in mind the power-to-weight ratio of over 250bhp/tonne, which canes almost anything on the road barring genuine supercars and bikes. Obviously FWD is a disadvantage off the line, but in another way its an advantage because once youre up to speed and wheelspin is no longer an issue, you lose less through the transmission than 4wd or RWD, so more power on the road and less wasted. Plus its a bit lame I know, but who wants to be forever losing the back end on country lanes every time you give it beans? FWD much more controllable, up to about 240bhp. Any more than that and its too much for the car Id say.
Just off the top of my head, I reckon it feels like itll consistently do 0-60 in the 5s somewhere, 0-100 in 12, 1/4 mile in low 13s. Hopefully on my gearbox itll top out at around 155pmh