Hatch versus Coupe Cat Back Exhausts

This is sort of a follow up to my previous post (6th gen cat). I have answered all of the questions asked in that post, but it has raised a new one.

I will now have a "custom" setup, in which I have a 6th gen hatchback with a relocated cat (moved from vertically mounted within the header to horizontally mounted after the header). My question is this: will cat-back exhaust systems intended for use on the 6th gen 2/4 door models fit this setup? From the engine to the back of the cat, my setup will be identical. I am not sure, though, whether the mounting brackets, pipe bends, and even pipe lengths will match up beyond the cat.

If unsure, can someone give me the dimensions for a 2/4 door cat back exhaust system?

Thanks..

I ran into the same problem on my hatch. If you buy an exhaust, it will fit to the collector on your exhaust manifold. If you buy a header, it will take the cat out of the whole deal, and just go header to exhaust. I bought a 2.5" high flow, unflanged cat from Jeg's for $100 and had a buddy weld it into my apexi exhaust piping right after the flange that bolts into the header, problem solved.

Technically, if you have $1100 you could buy an oem EX converter, bolt it into the header, cut the exhaust pipe short, weld the flange onto your cut pipe, and bolt the exit side of the cat into that.

To answer your question, no, adding a 1.5' converter to your piping will not work. I mean think about it, your entire muffler will be sticking out past your bumper...

Thanks for your response. I'm not sure about your last comment, though. On adding the converter - maybe this is where I am wrong - I thought that the VTEC model had the converter under the car, mounted horizontally. I thought that maybe if I move my cat to this position also, the catback intended for the VTEC would fit, as it would be shorter than that required by my original setup.

I think that my best (and cheapest) option is to buy a standard cat back, and take it to a machine shop that can cut and reweld the flange that attaches to the cat. I might also be able to just get a custom relocated cat-back system made up at a muffler shop, but then I worry about not having a resonator in the pipe.

Well why are you asking about this? Are you installing a header? If so just do what I did and have a machine shop weld it into your exhaust. You'll also need a nut welded into the piping as a hole for the second O2 sensor to screw into, after the cat. I bought one and it cost $7... Bring your sensor into the store and see which one it's able to screw into before buying anything.

I already installed the header - I am just working backward from there. I'd like to do the whole thing myself, without any cutting or welding, if possible.

I actually found a manufacturer who realized that people will tend to configure their exhaust in this way. Their cat-back comes to fit the setup I currently have, with an optional additional piece.

It comes with a cat integrated with the piping, or comes with one extra? Got a link? I may be interested in buying one too...

The cat is separate - which is nice, since I intend to have a cat in about 2 days out of the year. All flanged connections. Before you start laughing at the manufacturer, let me say that I am of the opinion that the manufacturer is not critical, so long as the specifications are met. In other words, if it's just pipe, I don't really care who made it. If sound is no good, you could always replace the muffler. And as an added note, I got my header from them, and it met all of the specs in which I was interested (bend radii, inner surface roughness, wall thickness). Good quality welds and coatings as well.

http://www.meganracing.com

If you're still interested, I'll let you know how my install goes. It may be a while, though, with the holidays and all.

BTW: do you know where I can get a harnessed "extension cord" for my O2 sensor cable (so that I don't need to splice any wires, I can just plug and go)? The last thing I need to throw a check engine light is a loose connection.

I wouldn't have cared about brand names either instead of going through all the crap I've done to get my exhaust setup working properly... Go for it man, $350 for an exhaust is cheap. The pipes will probably rust though, not being ceramic coated...

Oh about your sensor, I had to extend mine about 2 feet and it never threw a cel. Just strip the wires and connect them with butt connectors, then tape it up and you'll be fine. Make sure you use the same gauge wire though.

Actually it is $240 - they mark it up so it looks like they mark it down when they sell it to you. I will give it a shot. And I might have to break down and strip some wires. Thanks for your help - and nice hatch, by the way.

Yeah thanks, let me know how it goes and take some pics man.