500hp might be a lofty goal to start with, but it depends on how much money you want to spend.
All that is really weak about a ka24e in a boosted application is the pistons, followed by the rods.
The rods are actually pretty strong, however, and there are owners running 400hp on them. I have also read about them bending because of detonation, so tuning has to be good, otherwise, you can buy, for example, Eagle rods. There are several makers of rods.
I have heard that if you want more than 300whp, then just get better rods. That way when you want to up the ante even more, your engine can take the shot.
The pistons are first on the list to go, and there are several forged ones available.
As far as I know, the rest of the motor is stout, and can make alot of power.
AMS makes a performance rebuild kit for turbos. Google it by name.
The timing chain guides should be replaced with metal backed pieces, and not the platic backed ones.
Also, and this should actually be the first thing you read, check out the stickies in our turbo ka forum...
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Modified by seang at 9:00 PM 12/31/2009