I had the motor out to deal with a spun rod bearing. I replaced the crankshaft with the same Scat 331 striker crank that came out. I noticed that my original poly mounts from Summit Racing(their in house brand) had literally melted due to to how close my shorty headers were to them. I spent more money on new Prothane poly mounts. Now I feel more engine vibration from 2k rpm's to 3k where it smooths out. The crank, harmonic balancer and flywheel have the same balancer factor(28oz) as before. Rear diff angle is the came. I can feel the vibration even when the car is in neutral. I'm thinking and hoping it's because of having stiffer motor mounts than before. Have other people noticed this? It's really kind of annoying. I originally had rubber mounts but over time they collapsed allowing the oil pan to extend below the frame rail. I found that out because I was out having fun on some rough roads where I bottomed out the suspension just right to knock the oil drain plug loose where upon all the oil leaked out causing the motor to seize. I'd really not have to go back to rubber mounts but?