Where to start, im going through this as well.
Maybe start with defining what you want from a piston and what alloy you want to use, as this will play a role in what piston to wall clearance you run because of expansion, based on how much power you intend to make, and if you want to spray NO2 ever.
2618 alloy, Expands more but is more resistant to cracking from detonation. From my reading many people making good number in the US number have said Wiseco 1400HD are arguably then best designed on the market for out cars in this range, lots or material around the pin where the standard wieseco's have been shown to crack around the pin and skirts, but then again there is likely more people using these than any other piston for a 4g63 so your going to get things like that showing up purely because of the number of them out there, the 1400dh does appear to address this problem however. Guess you need to weigh up the weight of the piston against how strong you want it to be as these are a bit heavier than the other options.
4032 alloy, low expansion but more brittle. I'm thinking of it as a good medium between a factory cast piston and a 2618 piston that ill have the idle the car for minutes to let the piston to expand. With this alloy you can use tighter PTW clearance, for me this is a plus as i want to be able to just drive the car, not treat it like a race motor and have to warm it up every time i cruise down the road. Of course it wont thrash it till warm but i don't wan to have to idle it for 10minutes to go the the shops. If your building a w.e thrash toy or race motor this may not be a problem.
Mahle make a good 4032 piston and i found a number of cases people running them and being happy at 6-700whp. I believe this what i will run. They also make a 2618 piston as well, but id only use their 4032 piston, if choose something else if going a 2618 piston.
Then rods you want as light as you can to hold the power you see yourself making. I'm not going to bother with aluminum rods, more for a race motor that get pulled down a lot and inspected. Eagle are light, very well proven and also cheap as a bonus. Otherwise for not much more you can go something like a Manley H beam, but off the top of my head they weigh a bit more. Then there's carillo, pauter, oliver, but unless you building 1000hp specialized motor it doesn't seem necessary to spend close to $1K on rods.
