My old slapper had around 220,000kms on it before the previous owner decided to throw a GT35, ecu and a few other things at it. He went easy on it, and only made 210kw to start with. This was about 7 years ago.
I then purchased the car, made a few changes and retuned it. Made 255kw and had a hard time every time it was driven. I ran 12.0 @ 117 on street tyres. This was 3 years ago.
Last year i slid a camshaft into it, changed valve springs, made a new dump pipe etc and retuned it again. Made 303kw, 680nm (17psi) on DD roller with mixtures fat at 11:1 to keep it alive. I ran 11.6 @ 122 in a manual 31 being fairly gentle with a 1.79 60.
Now the heads never been off this engine, so the gaskets nearly 23 years old and it doesnt push a drop into the catch can. Obviously i could make more power but its at its limit of reliabilty now, and i cant be bothered fixing it at the moment.
Id rather push an old rb30 thats been babied around by an old fella than a stock 25 thats had every dickhead and his boyfriend rape it.