Ok well there are plenty of 306 strut braces on ebay, both new and used, depends on budget I guess.
Exhaust, plenty of used stainless ones about on here and on ebay, or if you'd prefer to have a custom one made could take a trip to Longlife or somewhere (theres one in Stonham Aspal I think). For the cat, you could always knock out the internals...as long as it 'looks' like theres a cat there it'll pass MOT lol. I've used systems with and without cats though, and I didn't find the cat was that much of a problem on a stage 1 HDi so left it on my last couple of HDis and just fitted stainless cat-backs.
Not sure on black wheel bolts, not something I've ever looked for! As long as the spec of the bolts is the same as standard they should fit, probably find those on ebay too lol.
Edit - Also, maybe it'd be easier if you started a project thread about your car and plans.
Exhaust, plenty of used stainless ones about on here and on ebay, or if you'd prefer to have a custom one made could take a trip to Longlife or somewhere (theres one in Stonham Aspal I think). For the cat, you could always knock out the internals...as long as it 'looks' like theres a cat there it'll pass MOT lol. I've used systems with and without cats though, and I didn't find the cat was that much of a problem on a stage 1 HDi so left it on my last couple of HDis and just fitted stainless cat-backs.
Not sure on black wheel bolts, not something I've ever looked for! As long as the spec of the bolts is the same as standard they should fit, probably find those on ebay too lol.
Edit - Also, maybe it'd be easier if you started a project thread about your car and plans.