from what ive heard the catted header has a less pronounced rumble compared to the catless due to a more rounded bend to make room for the cat. as for location i dont think it matters but most people do keep the 2nd one (front pipe) by leaving it stock

 

I believe you have less of a chance throwing a CEL with the catted header. I’m running JDL’s dual resonated front pipe with their catted header and never a CEL. Almost went the same route because like you said it’s cheaper. Even have some defoulers I never installed still in case I went with the catless header.

 

Which defoulers did you buy?

 

Header with cat will be very unlikely to throw CEL, as that's the cat that is actually being monitored.

I'm currently running a catback paired with the JDL dual resonated front pipe and it sounds good. My first gen i went full catless but had an actual muffler, wasn't too loud but a bit of rasp. I'd keep at least one cat unless you're going full racecar. Once my warranty is over, i'll be going JDL EL catted with their overpipe, so almost same setup.

 

I can tell you catless headers with the JDL UQ front/over pipe still has some odor, especially on cold starts. It’s pretty minimal once the cat warms up. Deleting that cat in the headers does make the car dramatically louder if you have an aftermarket exhaust.

 

Generally speaking:

• For performance, it's best to have your cat as downstream in the exhaust system as possible to minimize disruption to exhaust flow.
• For cleanest emissions, it's best to have it integrated into the header to warm it up quickly.

 

The more forward mounting keeps the cat hotter to do its job more efficiently. Moving more rearward it will run cooler and be less effective. That is why some people say there is still a fuel odor when running only the front pipe cat. Being less effective also makes it more prone to varnish and clog up the cat, reducing performance in the long run. IDK how common it os on this platform, but that is the basics of it.