I have the standard jetpacks on my LA upgraded to rank 4 and I thought for awhile that I was getting improved performance with them. Turns out this was actually placebo on my part. My dad also plays this game and he is mostly an Engi. I met up with him at the warpgate and we compared his stock jetpack (rank 1) with my rank 4 and they turned out to be exactly the same. Same flight distance, same fuel regeneration time. If you check your cert screen you'll find that the difference between stock and rank 4 jetpacks is actually quite big. This shouldn't be happening.