Longtubes will give you more torque, more hp, and overall are better for performance. Shorties are good for having clearance, if that is an issue, but I don't think they perform as well. Longtubes generally cost more if you are looking for ceramic coated too I think. I did see one dyno article where shorties gave a higher peak hp at the very top end, but torque was less. I would go with longtubes in an older car for sure, but that's me
Exact opposite opinion here: I will never go back to long tubes. They are a pain to install, most require a drop bracket for p.s., they hang too low, they are in the way, and the power is difference is simply not worth mentioning. Buy hi quality shorties, stage 8 locking bolts, and forget about them.