a standard sti8 bottom end will take 450bhp.
One problem you may have is if you are planning on using your existing heads, the STi8 heads have vvct which require additional wiring.
To be honest dont want a car built by somebody else and i can do the same quality build myself for way less money. Yeah it would be easier but way less fun and i wouldnt be able to say id built it myself. I just need to do my research and make sure i know about anything that could be a problem so im well prepared when i start it.
ah right i get ya.
tbh ej257 block, rods, pistons, heads, supporting mods and supporting turbo will prob be the best route, responce and reliability wise for road use up to 450bhp.
after that the block starts to get a bit risky.
Well if it means reliablitly may be sacrificed at 450bhp id be happy with about 400bhp to 425bhp, if it meant its less likely to go bang.
and dummy question again here tidge but im assuming ej257 block is the later 2.5 one, i was thinking about this as well, but i was wanting the vvct heads so will need sti ecu and engine loom as well iirc. along with countless other things lol.
drop in an sti8 complete engine, with the right turbo and ancilliaries will get you 450bhp.
the standard sti (2002 to 2004) are forged, mine has been running at 450bhp for 3 years now.
If you are going to strip it, you could put aftermarket pistons in for future proofing.
But if you are going to the trouble of changing pistons, as long as you have a strong block (semi closed or fully closed) it wont matter what age of car it comes from.