hi ..

if i add couple of things to my GS430 like header and a exhaust will the computer detect these changes even if i take them out ??????
am asking cuz my dealer said that if i add any thing to my car i will lose the warranty !!

 

The ECU wont care too much about the axle-back exhaust, but the headers do make a difference. If you take out the headers out, your ECU will be reverted back to original spec basically. No change is really permanent because the ECU can 'relearn'.

And besides, if something goes wrong, they're going to have to be the one to prove that your mod did damage to the car. You dont lose all your warranty, just the warranty against engine/mechanical.

 

By adding an exhaust will not effect anything to make it run bad (at least any decent exhaust). Some Lexus shops even install exhaust and have no issues.
I can't see where even headers should affect anything.