ok here will be my exhaust setup

jet hot longtubes- stock cats hollowed out- 2.5" x pipe- 2.5" bullets, then either turndowns or over the axle. ok now i will need 2 o2 extensions right? what length should i get? how many simms do i need? anything else i need? would my stock cats just get welded to the collector of the headers? since the jethots dont have flanges?

 

if you are running cats...you won't need sims

there are 4 sensors, two in front of the cats...vital to the engine's air/fuel monitoring system. and 2 after the cats to monitor the efficiency of the cats. if the cats are gone, those sensors will trip a code, but the code does NOTHING for performance...just the nuesence of the SES.

tech support on thunder racing or tbyrne should be able to give you the proper length extension.

how they are attached is up to you. i would suggest welding a 3" to 2.5" reducer to the cats, then the reducer will slip into the collector...and run the rest of the exhaust behind the cats...Xpipe etc

 

Just a bit off topic. I thought that the rear o2 sensors were supposed to trip and code if the cats are hollowed out, it would make sense. But I hollowed out my passenger side cat the other day because it was rattling really bad. Before I hollowed the cat I had a check engine light, after I hollowed it out the light turned off. Any insight? I thought that was really weird.