Exhaust blowing

[Bobbit]

I think my exhaust is blowing, listening to it I think it is the front pipe, but not 100% sure. can anyone offer any good tips so I can tell for definate? I\'ve blocking the end but cannot see anything for definate. Also got a Racing beat exhaust system, so if i do need a replacement which do i get? I\'ve looked on mazdarotaryparts and rotaryarts and I think it may be the HKS one, but again not 100% sure.

Thanks

Rob