Absolutely replace that exhaust. An easy to do HP mod. With a supercharger, a must.

 

I have a question that's somewhat related to this topic. My Kooks ORY is advertized as 3", but where it slips into the catback it's reduced, I guess to 2.75", or maybe even a little smaller. I guess that may be typical of most all Y-Pipes, but I wondering whether it would be a signficant restriction and whether some people cut that off and join their Y-Pipe to their catback in some other fashion where it would actually be 3" all the way back. It did mate up perfectly to my GMMG exhaust.

 

The cat is 3" and then it goes to 2 1/2" to the muffler. The car came with the current setup after the cat. I know the HP is down and thats why i am looking for a cause and i figured the exhaust might be part of it. The 42lb injectors are being delivered tomorrow so i'll get it tuned for the new injectors and get rig of the fmu and we will see where we are. The car came stock with 275HP and with the supercharger it should add 110HP for a total of 385 if the 40% minimum gain is right. The car has 100,000 miles with no internal work done that im aware of, so i would think i need to find 50+ more horses. The engines higher miles might be the cause of most of my lower numbers.