Coil over help

I've searched but come up with with little except for a ton of for sale ads here.

Can someone explain in simple terms the difference with regular 2.5 coils and extended travel?

I'm going to replace mine soon and want to order the correct thing. I currently run TC UCA, some kind of spacer and 285's. I can't tell what coils I have. Here are some pictures of my current set up.

 

wow, guess I'm shooting blanks here.........

 

They look like stock coils on billy 4600's ti me. If u have have the OR pkg then those coils are progressive and should not be preloaded much, but if ur getting new coils that doesn't matter. I dunno about extended travel and such

 

Thanks, so extended travel is just to add more droop? I really dont need that, guess I'll order up some regular 2.5's.

Are the Resi shocks worth the extra or is that for just constant abuse type of driving vs. 80 street 20 dirt driving? Thanks