I haven't noticed any cold start issues living in one of the coldest capitals in the world lol. Yet to stress these in true winter temperatures but -5°C start was as normal as +40°c that we have been having lately. Winter where I am will really show if extreme cold start has any issues when we get -40°C and lower.
As for fouling, I have driven a good 5K km on the 27's I'll pull one out and inspect for white residue but I suspect if the stock and 24s are blowing due to heat, the 27 is unlikely to foul with heat high enough for it to self clean or compromise a hotter plug. No clue why Terry has the 24s rather than the 27s on the site but I know the very popular
hks upgrade is 2 steps colder than stock just like the
denso 27s.
Will report back when I get a chance to inspect a plug or 2; 5k km should be way more than enough for signs of fouling plugs if they are indeed too cold for the motor.