I've had this done now for about a month. Cold starts are going to be rough because you have removed something from your manifold on which the ecu thinks is working properly. When I start my car it goes to about 2k RPM then drops to normal - faster than what it did with the VTCS but normal nonetheless. My idle is a little more erratic but what do you expect when you're allowing more air into your engine than what was originally intended. Basically, what I am saying is that your car is going to run like crap until it gets warmed up - even more so if you've removed the TB coolant lines like I have. I see it this way, you can either start your car 10 min. early and let her warm up or just drive around at or above 3k RPM until she's warmed up. I get all sorts of weird hesitation and things when she's cold but as soon as I hit 3k RPM or once she's warmed up she runs just fine. Oh yeah, I an assure you I do not have any vacuum leaks - it's been checked by my shops and by certified Mazda techs and a Mazda dealership (it was fun explaining to them what I had done, but they checked it out for me for free anyway). If it means anything, I actually still have the VTCS actuator still plugged in but it isn't connected to anything (just hanging there). When that's my little rant...
For those who don't want to read: Removing VTCS will cause funny idle and rough driving when car is cold due to larger than average initial airflow.
