i wouldnt recommend the .21 buggy engine in the truggy, i raced my x2with it last weekend it was fast, just didnt have enough bottom for a few of the jumps, as far as the straightaway it stayed with anything, it was just on one of the jumps it just didnt have enough, i went lastnight and practiced with my x2 with my os speed with jp3 and it was much stronger on the bottom and had no issues with that jump, i like the grp in my buggy alot it has more then enough bottom in it, just gotta run the right pipe and right plug and insert, if you wanna run a grp tuned i would recommend it for the buggy and just put your speed in the truggy, or get a speed for the truggy i sell them on here for 400.00 shipped or ebay for 400.00 plus shipping