Turbo and intercooler make these engines a lot of fun to drive and the most common thing people do to these engines is lug them at low rpm under load.
Heat is not a problem with this engine, a factory FJ40 rad 3 core is plenty.
The key when driving is keep the revs up and this will help drop the EGTS(exhaust gas temps) and thus reduce temps.
They are definitely a tight fit in a mini and a fair bit up tunnel cover and floor mods to make it fit, otherwise you will love it.
And on the extra cab we did, a marlin crawler box was a must to get the front drive shaft angle within reasonable angles.
We at Raddcruisers sell the Denco turbo for this engine, boost is a moderat 8psi, but can be bumped up to 14PSI.
You love this in a mini truck, being a non turbo motor it has a compression ratio of about 20 to 1 which makes it crawl through just about anything with out touching the throttle. This cannot be said for the 13BT or 12HT which at turboed and run 18to1 compression.
Rob