Could I use M6 bolts instead of M8 for exhaust to manifold?

[gc123]

i may have read this wrong but i assume you mean rather than tap to m8 you have access to fit 6mm bolts and nuts ? if so with proper washers then you could do it or drill out to m8 and fit 8 mm nuts and bolts either way would work. seen it many times when visiting exhaust centres, as long as the correct gasket is used.

doh beaten to it