10:1 and 9.4 to one. Aside from that obvious difference, any benefit to running one or the other. Say I had a set of both in my possession, which one would be better? I would have to slightly bore (1mm) to fit the paj pistons, where as the ralliart pistons would fit straight in. Is the extra .6 of a point worth the extra cost and labour to fit the paj pistons? How about quality and reliability of the paj vs the ralliart? Are either of the two chunkier or better constructed?
Cheers,
Aaron.

Your block condition may dictate which piston you use. ie Bores good use the Ralliarts and save money, or if the bores are worn use the oversize Pajero pistons.
There would only be a very slight gain with the Paj pistons. I would do some head work while you are swapping pistons this would help alot more than the compression increase and some #7/15 cams while it's apart.

Cheers Dave

Thanks Dave, the block is brand new, so ralliarts it is. Where would you recommend sourcing quality cams? Heard too many RPW horror stories to jump straight in.

Aaron why will u have to bore the block to fit the pajero pistons? The ACL Mahle version of the DOHC pajero pistons are available in STOCK bore size as well as 0.5mm and 1mm oversize.

Well, I may be able to get my hands on a new set of pistons cheap, that's all.

I have used MIVEC 3.8 pistons, they should go straight into 3.8 block without boring i.e just a hone?