should I change gears or tranny???

You are correct, the only "ill" effect IMO is higher fuel consumption and engine wear. My Dusted has 3.91's in it but its not a road car so I'm fine with that. My daily driver has OD and is better suited for what I use it for. I fully understand what you're getting at and I like your viewpoints. If I can score a 518 I'll go that route but if I don't find one in a reasonable amount of time I'll do the gear swap.