My T runs just fine with 31" tires. I had an open element filter on it for a while and although it definitely sucked more air (it was definitely SUCKING!!), I felt that was negated by the high air temps under the hood. I put the stock air box back on, removed the restrictive elbow from the fender and use a drop in K&N panel filter.
I feel it runs very well on the highway for a 4 popper and I still get around 22 mpg. Not bad but hey...my "other" truck only averages 15 mpg if that.
hth

joel

*1996 T100
2wd,long bed w/5speed
Borla Cat-back
*2002 Z28 Convertible
*2002 Lightning
*2005 Trailblazer