If i'd won the lottery, i'd buy forged bits, but i dont want to spend more on the engine than i planned for the whole car. I can't warrant big money when not going for big power.

I've spoken to an engine builder who supplies new standard pistons for all cars and he's checked some diagrams.

He gave me a list of 12 engine numbers from which i can use the pistons. They are 81mm bore, and all have a 19mm pin.

He then gave me a list of 12 engine numbers where i can get 20mm pin pistons, identical to the ones above apart from pin size.

He told me that either would lower CR to aroun 9:1 but the 19mm pin would be easiest to fit, and stronger since i wouldn't need to machine the pin bigger in the rod. I can only be more sure once i've bought an engine and given him exact measurements he asks for.

If they drop it to 9.2:1 and with a thicker gasket at 1mm that drops it to 8.5:1

How much boost am i likely to run on a t3 at 8.5:1

Am i right in thinking to get a bigger exh housing to flow more at same boost?