I have a 2008 Trance X frame and it should take 7.25 inch rear shock. This will be my first full sus bike.

When they say 7.25 inch do they really mean it or would a 7.5 inch be compatible? 7.25's are much more difficult to get hold of.

Any advice appreciated.

7.5 inches = 190mm
7.25 inches = 184mm

I've never even heard of a 184mm shock. Are you sure of that figure?

Unfortunately yes. Just not sure if the 5-6mm will make a difference.

Yes it will make a difference.

Will You notice that difference? well, it'll probably steepen the head tube a touch – I would imagine though that the difference probably isn't much more than the difference made by the length difference between difference forks of the same travel.

The other thing to check is that none of the linkages would hit anything if extended further than designed due to the longer shock.

Only one real way to find out… try and see…

What's wrong with the shock it came with?

A potentially expensive mistake. Damn the learning curve!

It came with no shock, frame only.

Ahh, I see.
Don't Mojo do custom length Fox shocks?

Mojo, will check it out.

Thanks, back to work.