My '75 FJ40 has a 2F with 6--->1 headers. After driving for more than 10 minutes, the driver's side apron is hot to the touch, while the passenger's side is only warm. Needless to say, the firewall and floorboards do an effective job of heating up the interior. Could the exhaust pipe from, say, a 2F FJ60 be modified to work with the stock FJ40 exhaust manifold? Would it make that much difference? (since the exhaust pipe is double-walled, I think) Has anyone had any success heat-shielding the exhaust on an FJ40? Ideas?