I did that mod on my truck last year, you do get a little better flow going through there because that heater coil is so big. The main thing is it will give you alot more acurate boost reading, as for warming up, no difference, the only real purpose from what I was told was to cut down on some of the white smoke when its really cold out. I nerver realy noticed much difference in mine, heck maybe mine wasn't even working, normal cold weather smoke the first 5-10 minutes of running then its gone.
