I recently installed a flowmaster exhaust and now I realy notice the MDS, atleast I think that is what is making the weird sound, it truly sounds like I am running on 4 clynders, is this normal?

Also does a programer void the factory warrenty?

 

Yes its normal. A programmer will not void your warranty Just return your truck to stock when ever it goes back to the dealer. MDS delete is awesome!

 

Everyone has bi*ched about MDS and aftermarket mufflers/exhausts since the thing came out with the '06s!

A tuner does NOT effect your warranty unless the dealer can show where the tuner directly caused the failure/issue. But like RaiderJay said, return it to stock before going to the dealer to be safe. If for no other reason, you don't know when they may update the PCM as part of a TSB, routine update or recall...