IMO higher milage engines wont take bigger turbos any worse then lower milers, a bigger turbo puts less strain on the engine just tootling about and when on boost they cylinder pressures can be less for same amount of power I Td04ed mine at 160l (135k in km and rest in miles) and ran it a 1.5 bar for 30k miles !! then put back to ct9 and sold on and car is still going now. The important thing is to warm it up (as with an car n/a or turbo) before abusing it, and regular oil changes (every 2.5-3.5k i did) To be honest i wish i still had the car as it was as it got a regular 40mpg and not alot on the daily commute and local fast cars could get near it. so 1.2 bar on a 200k engine should be fine