Any thing obvious here?
The car did this from new until I got the wheels aligned.
It is now 120K old, so I am wondering if it might be anything else.
MY06 STI.

 

I had a similar thing recently mate it was the driveshaft popping out under acceleration

 

Did that make a noise of any type?
How did you find out that was the problem?

 

didn't make any noise no only found out when the shaft stripped the threads and lost drive altogether was like the clutch slipping new driveshaft on an no problems now worth checking

 

how worn are the tyres?
if they are old and the alignment was out by a fair way the tyres will be shaped,
this is probably whats causing your issue.

 

Cheers for your ideas guys.

 

OK - Tyres are new Goodyear Fi Assyms.
Alignment checked and is OK.
Guy (at Elite tyres) suggested swapping front tyres over and see what happens.
Changed them this morning and it is now pulling to the left.
Problem solved.
Weird though.
Might change front to back if I can be Ars*d.