Hiya m8y,Have a look at my previous posts done on 20 November 2009 on the this very subject. Think I did them under bionic too. The parts I used were genuine VX ones and the average quote I got from 5 mobile mechanics was £175 plus parts and a minimum of 5 hours if the studs did not snap or were missing. VX recommend that you renew all of the studs and nuts anyway. Whatever you do don't use an aftermarket gasket, insist on the VX one that is a 3 layered metal one. Inthe end I had a closer look myself and it was not what they had said at all.
The Vauxhall bits list.
Loads of WD40 the night before. Best applied while it is WARM.
Manifold gasket - 24416110 £5.91 each
Front pipe gasket - 190499289 £4.55 each
Manifold nuts - 11082413 £0.26 each
Manifold studs - 90106924 £0.45 each
Exhaust downpipe nuts - 90570845 £1.50 each
No doubt plus the dreaded vat too.
Also 2 8mm x 60mm nuts and bolts for the Cat joint. Get some exhaust paste (FireGum) too.
The Torx bolts that hold the 2 heat shields, thats right, 2 on one side are monstrously difficult to get to and are usually skin losers.
Use heavy axle stands or solid blocks on level groung and a heavy duty trolley jack too, at least a 2 tonner.
All I can say m8y is GudLuk, you will need it.
PM me if you need more info.