2005 prodrive wrx wagon

When the car is cold, every time I release the clutch and pull away i hear a dull knock as the load is taken but as soon as the car has warmed up a bit it goes away. It's not engine noise more like something hitting/knocking something if that makes sense.it sounds like its just behind the bulkhead toward the middle/ passenger side

I've been reading about engine and transmission mounts and was wondering the best way to check these and whether the symptoms described could be this

Any advice gratefully received.

 

it could be the top gearbox surport that is underneath the intercooler, if you take the intercooler off and get a nice big bar in there and check for excessive movement/ bolts are tight?

 

it could be piston slap, theres been a few threads about it on here, only when the engine is cold? search it on youtube see if it sounds the same. apparently its nothing to worry about.

 

Looks like it is the pitch mount under the intercooler, could feel the movement and noise when clutch released, took off the mount and there is excessive
play between the bushes and the rubber, bodged it with a bit of superglue and retried noise gone..

ordered an uprated pitch mount to fit at the weekend.

Thanks for your replies....