I have the Tf 240 with the 1.55" spring, 135# installed, 1.95" height, 430# open at 1.25", 420# rate. I went with this option due to the 10 degree locks vs 7 degree. I don't run the MP 590 cam, but the MP 557 cam. Motor been together for 4 years now and haven't had any issues. I shift my motor at 6500 and it sees maybe 67-6800 at the strip on a day with really good air.