The old engine mount will work fine. However the problem with the Hyper ST is that unless you are using the Ofna truggy start box then you will have trouble hitting the flywheel. So my recommendation would be to get a 34mm flywheel at least and then it would work with no issues. Heck you can even use a Savage X aluminum flywheel with the included collet and it will work great!. The cool thing is that the Savage X flywheel only costs about 9 bucks.