We have a Trailblazer and a 5 cylinder (aint full-grown yet) Colorado, even the 3.5 Colorado w/automatic (light 2-door truck) will get second gear rubber with 265/75 x 15 tires). In most reviews of Colorados the authors complain of no power--they have only driven the 3800# four door pigs powered by the 3.5-3.7 engines. Consumer Report tested a bunch of 4-door little trucks and their tests indicated the 4-door auto 4.7L V8 Dakota was a tenth of a second faster than the 3.5L Colorado (but a mph slower)in the quarter, and they say the Colorado lacks power-then what is the Dakota (i say chopped liver). The Trailblazer is heavy at about 4800# and somewhat slow off the line with 3.42 gears, but will wail when rolling. These engines are VERY stout in stock form (the 3.5 makes 220 NET hp - same as as a powerpack '57 chevy made in GROSS hp), compare the 291 hp Trailblazer to a 303 hp 5.3 V8 - not too shabby with only on 3/4 the cylinders and about 70 less cubes. In drive both these 4 inch stroke engines will (with wide open throttles) shift at 6000 rpm. Both my vehicles only get 22 mpg with their overdrives on the highway - so let us not get carried away with the economy claims.
DYI can tell you all about converting the computer to your truck. If you dont belong to "period correctness" thinking there is no reason other than the understandable $$ not to use the 4200 over a 250.
