ttss4

hi,
I've recently striped my engine out of my 1999 uk spec imp.
When i took the pistons out they didnt look anything like the
standard items i bought to replace them with.The pistons that
i took out have got pockets in them for the valves and the new
gen subaru ones dont.I do know the engine has been striped before
hence the re-build good job the bores are in a mess.
Is there any way of telling the difference between standard cylinder heads
and STI ones.

Cheers Ian.