What does GM still put exhaust manifolds and not 4 to 1 headers on their performance vehicles....do vettes come with headers? Is it true that headers help free up a decent amount of horsepower? It seems like it would be just as cost efficient to make headers and not manifolds....whats up with that....

 

I guess they leave that to the after market world or some other stupid reason.(stupid to us)

 

the cast iron keeps the exhaust temp up, therefor the cats get/stay hotter/hot = therefor, better emissions

 

If I'm not mistaken, the LS1 comes with a type of header. Still doesn't flow as well as aftermarket.

 

Newer LS1 cars come with manifolds that flow extremely well. Big collectors, etc. I've heard more than a few people say they were not impressed when they switched to aftermarket headers. This is usually with near stock cars and we have a local guy here running 12.15 @111 in a formula automatic car with a good converter, slicks, skinnies, exhaust, stock manifolds, a filter lid and not much else besides the typical plugs/filter/synthetics, etc...

 

I think a lot of it too is the fact that exhaust manifolds are good for well over 100k miles, and manufacturers have to consider longevity issues before horsepower often.

Also, what would be the fun in buying a car that already had an awesome flowing exhaust and intake...

 

yeah you have to also think that they could have quite easily machined better flowing heads, intake, exhaust but then i think they might be getting more then just a few angry corvette owners going wtf why are you building a car half as expensive as mine that can out run me.