coated or uncoated?
I agree.
Coating your headers will keep the temperature inside the engine compartment down, it will move the exhaust gases a little faster but mostly it will prevent them from rusting. I haven't seen any data to back this up but I am fairly certain that for a stock/street type car, the coatings don't really give any noticable performance increase. By increasing the temperature of the exhaust gases within the header you can THEORETICALLY increase the speed of the exhaust gases which will effectively lower the exhaust backpressure somewhat. If you really are looking for more performance out of your header, make sure you get a header that is tuned to your engine in terms of the diameter and length and collector orientaiton. That will actually help a lot more than any small gains from the ceramic coating.





