Ever since I got rid of my 3rd gen last year I have not really kept up on the 4th gens and instead of searching though 100's of threads for little tid-bits of information I figured I could just compile it here. I am considering putting another drag bike together this winter and am thinking of using a salvage 4th gen as my starting point. What I am looking for is any information/experiences with what kind of power the stock motors can handle, mostly rods/crank. I am thinking of going with 13.5 drop-ins but may consider a 2-3 mill build depending on cylinder wall thickness. Also could use any info on the stock valve train as far as what kind of rpm/lift it can handle. Pretty much any info is welcome...lol.