Ok so I have an 07 ls with sai. Obviously I cant change the exhaust mani due to my sai. So I was curious, is their a down pipe that will fit my car without reflashing the ecu or throwin a cel? I assume I need one with a cat so that i am all legal.
Almost all the DPs for cobalts will work. As for cat or catless it depends on your state. If you have to pass emissions then you will need a cat, otherwise its your choice. If you go catless and want to avoid a CEL I suggest a 90* O2 Adapter for the sensor. I got one on ebay for around $20 and it works wonderfully.