has anyone ever tries to take out the slider rails under the seats to lower them? how hard is it?

 

You can make shorter brackets and bolt it to the floor.
How much lower do you want, you can also pull the seat out and remove foam from the seat bottom to get .5-1" if you really hack it up and hammer the seat bottom.

 

there is 2" of foam in the bottom so you can get more than .5-1"