You can get heated leather seats on a SR5 from an aftermarket shop. My dealer quoted me $1900 for heated leather seats. As for the nav, I understand if you have the JBL package(EJ), you can get the nav head unit (ordered from parts shop or there is OEMvalue.com that has them, I have no FHE with them, so I don't know how good they are), that is plug and play with the jbl system. The only other things you will have to do without on the SR5 is you won't have the optitron gauges(blue gauges instead of orange), and I believe the steering is just tilt not tilt/telescoping. I am sure there are a few other things missing on SR5 that is on the Limited. But can't remember them off the top of my head. Goodluck.