exhaust rattle/buzz

[shifty]

Ok im at my white end now I have a rattle slash buzz coming from my exhaust I have a full stainless setup header to catback I get a small rattle with my resonated hf cat but when I fit my decat its unbearable I've recently swapped out my toyo header for a racing beat one which cured other issues and rattles but not this im not sure where to look next and its driving me nuts I wanted my decat on for yesterday but it sounded awful and when the mashal doing the sound test said my girls and hf was pathetic I was even more gutted.

[bse]

Put the car on jackstands, engine on. Rev it and see where the rattle comes from. It may be a flange to flange mating problem, a heatshield one (carback\trunk) or the pipe hitting the under braces.
If you have access to a lift then it's even better.

[shifty]

I had it up on stands with the engine running and I can hear it right from the header but can't see it touching any thing

[bse]

See if it's on tight where it mates to the midpipe. Otherwise check the air pump assembly and what's around there...

[shifty]

Bolts are tight did them myself then did them again then again after reseating and bolt replacing.
will check the air pump next would it be coming from the pipe that goes to the header as the air pump only runs few a bit also could this be a engine mount issue

[bse]

Engine mounts would make the whole car shake. Different parts may have different flange thicknesses. Springed bolts may help. Otherwise just use some crayons to see where it may rattle... colour where the midpipe passes close to the various parts it may touch. I'd also double check the header installation and tighten it up.

[shifty]

will do spring bolts well washers are fitted between header and midpipe.
The crayon is a nice idea but I cant see it touching anywhere I started her up rattle straight away and I stck my hand in everywhere I could see might (before it got to hot lol)

[bse]

I'd check the headers again, especially if it happened right after the install.

[shifty]

Thing is I had it with my toyo header then with my racing beat one.

[bse]

If it gets worse with a decat midpipe vs a catted one then you know where to look