I am getting a new header and cat for better performance. Right now I have an ebay 2 inch piped header with stock cat. I am getting an amazon package with a 1.75 piped header and a high flow cat. Will I notice any horsepower gains or losses with the 1/4 inch difference of piping between header, and a new high flow cat?

 

lol loss that's like the stock ID of a civic dx which is super small why would you do that to your teg ? the stick pipe size is 2''. in essence you're back pedaling hard with 1.75