Go for it mate, if you find a nice 06/07 model that's well kept no damage with low kms, don't think twice because someone else will nab it in the meanwhile.

My two cents though - Check if the timing belt/spark plug service has been done, if not try to get them to do it for you for free for you to buy it.(not sure they'll do it for free but worth a try!)... You should do this service at 4yrs or 100,000kms whichever comes first...but you will find that most low km 06/07s haven't had it done (stingy owners + not reached 100,000km)...for peace of mind you'll have to get it done after you buy it anyway if they don't know if it's had that service done(or when it was done!). If it's been done then all good.

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06 STi: 337hp @23psi on E85...
06 STi: 309hp @22psi on 98ron...