G'day, new to these forums, hope you guys can help.

Sounds like I've got a pretty bad exhaust leak, but when I switch over to lpg the sound disappears. Is this due to the differences in lpg/petrol - maybe the different pressures affect the exhaust differently? or have I got another problem on my hands. I can't find an obvious leak although my cat looks a bit flimsy to say the least.

I originally thought the problem was one of my valve cover bolt gaskets, because one had melted and there was a 'heat spray' damaging the finish on the valve cover, but I changed all of them and the problem remains.

Any suggestions or input appreciated, cheers

Sorry just read the forum guidelines, this post shouldn't really be in the 6cylinder workshop, but I haven't worked out how to delete it! Sorry!

Update:

Definately was an exhaust leak, a pretty big one at that, but I'm still stumped as to why I couldn't hear it on lpg?