I searched and found nothing....I know diesels have 4 inch cats but im guessing thre alot different?? Just wanted to know if anyone knows or heard of anything?? Also if not, could it be possible to find a 3 inch inlet n outlet cat with a 4 inch center and cut the ends off and weld 4 inch pipe to them?? Just a crazy idea but might work? Let me know and TIA!!

 

try kteller the make custom 3" cats

 

Do you think he can fab me a 4 inch?

 

Cats are generally a block of rubidium and other rare materials used as a catylist, which is a grid for air to flow through. You could take a high-flow cat, chop off the ends, tehn weld 4" in/outlets, but you'll usually see the biggest restriction from the grid itself. Your best bet would be finding a high-flow cat for a large-displacement motor, but many are just large, flat deals (grid at an angle), or they may go to 2 smaller cats.

You could always drill the cat out a bit, hope it still scrubs the air, but thats sort of illegal