mate it sounds like what mine had, leaking at front between centre pipe and manifold.
Start it up, put your palm over the end of your exhaust and it should be so strong that the pressure blows your hand off the end after a few seconds.
If there is no pressure and you can here it hissing then your exhaust is blowing.
Antoher option if it is blowing is to get some shower gel and rub it over your seals on the exhaust (back box join, middle box join, manifold join) and then let it run for a few minutes. If it starts blowing bubbles then you have a leak somewhere.
Jake
Start it up, put your palm over the end of your exhaust and it should be so strong that the pressure blows your hand off the end after a few seconds.
If there is no pressure and you can here it hissing then your exhaust is blowing.
Antoher option if it is blowing is to get some shower gel and rub it over your seals on the exhaust (back box join, middle box join, manifold join) and then let it run for a few minutes. If it starts blowing bubbles then you have a leak somewhere.
Jake