I did longtubes about 3 weeks ago so of coarse I have no cats on the car now. Would one high flow cat at the back of the Y pipe be too restrictive? I dont have to have a sniffer test but they look to see if ones there and the location doesnt matter.

 

Hi-flow should do fine with little restriction. You can also gut a cat so it looks intact.

 

Im afraid if I gut it the shop wont put it on. I found a post about pypes mini cats so Ive thought about looking more into that, one on each pipe if theres room.