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Hey, let me start off by saying I know this probably doesn't make good sense, and I may think better of it.
So I have a 2002 EX EM2 with a D17A in it. standard ride height (and plan to keep it that way).
I drive a 3500 Chevy Express van for work. someone evil -might have- stole the cats off it, and -possibly- it currently has test pipes. I have got to where I rather enjoy that exhaust notes and noise. Don't worry I have no interest in dropping a 6.0 Vortec into my civic (as I like 30+ mpg, not 11mpg). But I wouldn't might a couple steps in that direction as for as exhaust sound. I replaced my cat about two years ago, and probably what to keep that as is. And don't want to spend too much as I mostly understand that isn't much power to be gained short of a turbo, and already have a little bit of a lead foot.
If I do play around with this, I would want to go with a side dump just in front of the passenger rear tire. Just because I think it looks good, which would mean a rather flat muffler (and resonator?) I guess. As far as sound, more or less I just want a larger pipe for lower/throatier sound? And if I just go catback the performance is going to be more or less the same? Anyone done something like this? Do I just need to ease off on the antifreeze I am drinking?

Here is what I have theorized, keep standard bolt flange at back of cat, upgrade to 2.5ish inch, place resonator in the large existing cut out of the frame just behind cat, follow normal routing back some, then angle out and place flat muffler (which not sure how flat I can find easily, or bolt in on tight and let it 'self tolerance') run short angled (maybe oval) exhaust to get out from under car.



as it currently stands and crude drawing of what I want maybe

 
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I'll entertain your idea. If it makes you happy and you do it right, it might be cool. I don't think I've seen that on an EM2 before.

Unless you're planning on going boost, I'd keep it to 2-2.25" exhaust piping. Beyond 2.25" is about the threshold when you'll start to lose noticeable low end without some supporting mods that'll add significant power (e.g. more than intake/header).

I forgot how much room there is downstream of the cat, but you might want to consider stuffing the rezzy and muffler close to the cat, then figure out how to install some hangers that'll support the tailpipe that dumps forward of the tire. Either that, or some round muffler where the rezzy is, then have a short pipe that turns 180-ish and dumps forward of the tire. There looks like there might be some room to have it do that turn at about the.. 1-2 o'clock position, then some twisty madness to have it dump where you want. Those extra bends might be enough to baffle some unwanted noise, but that's pure speculation.

 
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Thanks for the advice.
So you would say that with stock manifold, down pipe, and cat, stick to 2 or 2.25" pipe? I am not planning to do anything big to it.
I had not thought of reversing the outlet forward, that would open some options. And having looked around online, I am not seeing any mufflers to fit flat under that body without creating serious clearance issues (but there do look to be several resonators that are pretty slim). So using the resonator space is probably required to fit the muffler.

 
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yeah, everything downstream of the header, I'd try to stick to 2.25" as a max. Might be hard to find mufflers that have a 2.25" inlet though. 2.5" is def more common. I ran 60mm piping with my A'PEXi WS2 exhaust, but I was boosted for some time and I had a stage 1 cam. I lost a little bottom end, but not enough to **** me off. It was a chambered muffler, too, so that added some backpressure to keep it happy. 2.5" won't do too much harm, but you'll get better results from the 2.25 considering the nature of the D17

As far as low profile mufflers, N1 style (though, they could sound raspy or give that "angry swarm of bees" sound) would maybe fit, but again, finding one in 2.25 might be hard. Magnaflow has a 4" OD muffler with 2.5" inlet/outlet you could tinker with. The outlet looping around might provide some good backpressure, and you can always toss a reducer on backwards to go from 2.25" -> 2.5"
https://www.magnaflow.com/products/1...-muffler-10416

Either that or glasspack/cherrybomb the **** and call it a day. lol

edit: Okay, I'd never come across a D-series engine with a glasspack muffler, so I was curious. I found a video of a D16 with a glasspack, and honestly, sounds pretty damn good.

Edit 2: found a D17 with a cherrybomb. The D16 sounded better, but still not bad

 
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I ended up going with a Flowmaster 842580 muffler, which has the inlet and outlet on the same end, and I like the metallic sound of chambered Flowmasters, and used the resonator area. Raided the local O'reaillys for a bunch of adapters and pieces and cobbled it together (the polished stainless is from Summit). I think I have several small exhaust leaks and the VersaChem ExhaustSeal (though I followed the directions) seemed water soluble and largely dripped out of the joints from the condensation on startup. I might give it another go, or try and weld it up. Currently I just have it coathangered in place while I tweek it to make sure it will work well, hopefully I can get a hanger welded on to secure it properly in time, so forgive the appearance.
Overall I would call it an success, I definitely hear it when I put my foot in it, though basic cruising it is a bit more noticeable than I might like (we will see after I drive it overtime, how much it grows on me). But I think that is just how it works unless one take the cutout route.

The stock mid-pipe for general information is an 1 5/8" OD, not a 1 3/4" as several sources on the internet stated, maybe I can save a few people an extra trip to O'reillys,
Thanks for the advice and information

 
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That sounds about how I expected it would.