Help me identify this smell please

So my buddy deciced to do 3 things to his 02 GT at the same time. He lowered the car with sportline springs (265/35/18 all around), he changed the midpipe to a MAC O/R H-Pipe and he change the gears to 4.10's. He did this all by himself with my help (his pretty good with cars but not a mechanic).

Anyways the car drives fine except there is this nasty smell of burning rubber and since he did to many mods at a time we can't narrow down the problem. The smell is like burning rubber but its a got a unique rubber smell that is strong and stays for a while, I almost want to say friction smell but not quite...Maybe the brake pads got some gear oil on them by accident? or is the 4.10 install bad? maybe the sportlines are causing the tires to hit something. It was late at night yesterday when it was finished so we weren't able to see anything and were kind of tire. any ideas?
 
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