I have just been looking at some different seats from a totally different car and I am willing to adapt the runners to fit but was wondering what to do about the pre-tensioners, will they still work?

Yes. The pre-tensioners have nothing to do with the seats and are completely independant. The mechanism is in the reel.

Cheers for that Bockers, so the seats won't explode that's good news, now to find out if I can swap the receiver for the seatbelt (I'm just pressuming they won't be the same).