i have a dc4 99 ls cpe. i recently put on a skunk2 60mm/2.34" catback. now i want to work on the headers and cat. i know the oem header is a 2 piece and was wondering can i use the lower portion of the header direct bolt onto the ls upper header? how big is the collect on itr header? should i use oem itr cat or carsound?

 

No and if it did it would serve absolutely no purpose. Buy a real header!!

 

Yes, you can bolt the lower half of an ITR exhaust manifold onto the upper half of your LS manifold. The collector is 2" OD (the same as the LS), and it will bolt right up to either an LS or ITR cat. However, if you're looking for performance gains, you really won't realize any by performing this swap.