I've got A/C in my wife's ute. It's an internally bone stock A12 with a gazillion miles on it and enough blowby coming throught the breather it could double as a compressor. The stock carb didn't keep up with the blowby at idle so I bolted some solexes that I had to overjet. The A/C works good, even on this pathetic engine, but power is effected quite noticably. With the sidedrafts though, I'd say with the A/C on, it's like driving an A12 with a stock carb. The only downside to my setup is the small condensor... need to upgrade for more effeciency.