Exhaust suggestions - stock/HO

[Stealthlead]

Hello,
To start off my 91 MGM towards the HO conversion, I thought it would be best to start with the exhaust. I have a stock LOPO that runs good with 130k on it. I need this setup to run good with the stock engine and with an HO converted motor (or possibly 351) in the future. I'm looking for that low rumble and a catback system. I'd really prefer my tailpipes to exit straight and not dumped down, and visible when facing the rear end if possible. Also, this system needs to have functioning cats. I'm thinking Ceramic BBK shorties, a BBK X-pipe, and maybe a magnaflow system like this
http://www.latemodelrestoration.com/...Steel-Cat-Back
I also have a few questions;
1. Will there be any welding involved and if so, at which points?
2. Will I need to make any modifications to any other areas of my vehicle for what I have planned?
3. My car has the stock manifolds and single exhaust system on it still. Am I likely to run into the problem of the manifolds being extremely hard to remove?
4. I'm just curious but theoretically, will this improve or worsen my emissions?
Any help is appreciated!

~Stealthlead

[johnunit]

1. it's optional. you can clamp everything but welding is doing it 'right' and prevents leakage and sagging better
2. probably not. You may have to add a hanger on the trans crossmember but that's about it. I have to move the air pump check valve (very simple job) for the headers to fit but I believe that's a 351 only issue
3. I think that depends on if you have oil leaks. If your car is dry, WD40 it once a day for a while before you do it an pray, if you have leaky valve cover gaskets like me you've basically been lubing those threads for years and it'll be like pie.
4. Assuming you're running a 100% stock and original catted system with air pump, and you retain air pump functionality, you're unlikely to perform any worse as far as emissions. If your current cats are good, it should be very similar, if they're a bit worn/blown then you'll see an improvement/reduction in emissions.



I don't think a mustang X-pipe has been tested to fit. Given that the mustang H-pipe by BBK is an imperfect (but still workable) fit, I'd not want to be the guinea pig for an X-pipe.

Your best bet for the exhaust after the cats is probably having a shop do it. The system for using mustang parts is NOT just throwing a mustang cat-back setup on it, and gets pretty convoluted IMO.

Hope that helps a bit.

[mitymerc]

I don't think a mustang X-pipe has been tested to fit. Given that the mustang H-pipe by BBK is an imperfect (but still workable) fit, I'd not want to be the guinea pig for an X-pipe.

Your best bet for the exhaust after the cats is probably having a shop do it. The system for using mustang parts is NOT just throwing a mustang cat-back setup on it, and gets pretty convoluted IMO.

Hope that helps a bit.

I am running BBK Mustang shorties, Pypes catted X-pipe, single chamber Thunderbolts with fabricated intermediate pipes & tails (all 2.5")
It rumbles @ idle & is a RIOT when hammered. I can set off the alarms in parked cars at will.... LOL...

[Stealthlead]

Hmmm so basically I'd have to have some custom pipes made if I wanted a cat back? What about just dumping before the rear axel, would that be easier? I'd really prefer a cat back system but if its really that ridiculous to install I've seen a lot of people just dump in front of rear tires. And H or X pipe, whichever is interchangeable.

[johnunit]

Hmmm so basically I'd have to have some custom pipes made if I wanted a cat back? What about just dumping before the rear axel, would that be easier? I'd really prefer a cat back system but if its really that ridiculous to install I've seen a lot of people just dump in front of rear tires. And H or X pipe, whichever is interchangeable.

the combo for off-the-shelf cat-back is this:

foxbody mustang starter tubes

These are what my car has
http://www.summitracing.com/parts/BIG-53609FLT/

then a length of piping is added between that and the mufflers, it obviously varies between mufflers but mine are like 7 inches on the short side if I had to guess with 18 inch case mufflers

Then after the mufflers which must be "offset/offset" type, you have 2.5 inch Dynomax/Walker Impala tailpipes, which take you over the axle and most of the way to the rear bumper.

I don't have the impala tails mounted yet, so I can't tell you what would be needed for getting those pipes to exit the way you want.


I currently have my exhaust dumped before the axle. It's a bit loud and droney, but then I went with flowmaster 40 ripoffs (thrush weldeds) which are loud and droney on most setups.

In all, you'll need at least 4 hangers, and 8 clamps, unless you do some welding.

[Stealthlead]

I'm planning to do it the right way and weld it. I have a few friends who can help me out. As for the H-pipe, what should I be looking for? Can anyone else attest to if either of the above tailpipes will take me to the rear bumper?

[johnunit]

BBK 2.5 H-pipe is what I have, as well as a few other people on here. And obviously Mitymerc can vouch for the pypes X-pipe.

[Brown_Muscle]

You just need extensions for the impy tailpipes to exit straight out the back, that's what i did with mine.

[Stealthlead]

I just talked to my friend that said it would be no problem to get my system welded. So to sum it up: BBK shorties, BBK H-pipe OR pypes X pipe (Should I go X or H?), this extension between the X/H pipe system and the mufflers http://www.summitracing.com/parts/BIG-53609FLT/ , The muffles (Any suggestions?) and finally the Dynomax/Walker Impala tailpipes. Should this system be a good fit?

[johnunit]

yeah. remember those extensions themselves are not long enough. you'll then need another short length of pipe to get them to reach to the mufflers. Those are another mustang part, so you have to make up for the extra wheelbase of a panther.


What do you want for sound? Best advice I can give is type into youtube some basic stuff to describe your setup (HO catted, for instance) and then "exhaust" or "rev" and see what comes up. When you find something you like make note of the mufflers listed. Keep in mind the size of piping and tips, as well as the presence of cats and the aggressiveness of the cam all affect sound.

[Stealthlead]

I'm looking for that low rumble/growl that I hear a lot in the videos of fellow GMN members. So the question is, where to get that extra length of piping? I like this vid http://www.youtube.com/watch?v=oJNM0...ayer_embedded#!
I'm looking for the low rumble on idle and roar on open throttle I guess is the best way to put it

[Stealthlead]

What if I just went from the H-pipe and dumped the muffles with something like purple hornies? Would I still need extensions? I've been watching some vids of a few cars that have purple hornies.. they sound awesome. I know there LOUD but exactly how loud?

[1987cp]

Couple things -

First, write your local lawmakers and ask them to repeal your local emissions/inspection laws. Though, I find it weird that you'd be allowed to not run tailpipes if emissions testing is required.

Second, don't be surprised if you get lousy low-RPM resonance with a full 2.5" system. Resonance can seriously abuse your ears even if the exhaust note itself is very quiet. Some guys claim they have no resonance, but I think they're just deaf. If you're already deaf, resonance probably won't bother you. If you're not deaf, consider adding some sort of resonators to the tailpipes.

Third, guys need to remember that Maremont 339221 midpipes do the midpipe job without the extra bit of pipe the Mustang midpipes require. They're kink-bent, but I doubt that's usually a big deal. Extra bits of swaged exhaust tubing can be easily obtained from your favorite local parts emporium, or order them from wherever seems convenient.

[johnunit]

What if I just went from the H-pipe and dumped the muffles with something like purple hornies? Would I still need extensions? I've been watching some vids of a few cars that have purple hornies.. they sound awesome. I know there LOUD but exactly how loud?

Purple hornies dumped at the axle will be LOUD. I've got Flowmaster 40 knockoffs, a step or two quieter than hornies, and I barely get away with the sound level dumped at the axle. That's also with cats, which will quiet things down a good bit compared to an "off-road" H-pipe. You do also risk police attention if they notice you have no tailpipes. dumped at axle= dumped before end of passenger compartment, which is illegal in many areas and can be genuinely dangerous in heavy traffic, especially if you've got a car that is not running right and/or doesn't have cats.



Also, I don't really know what 87CP is on about with the emissions thing. In your application the only thing that really changes for exhaust is whether you need cats or not if you have emissions testing. An extra couple hundred bucks, yeah, but no real performance hit and your car is quieter and smells less, even if you don't care about pollution.

[1987cp]

:lol: Says the guy who says he gets in big trouble if the local cops think he has anything non-stock on his car at all.

Actually, I've got nothing against clean exhaust, or running cats if you want to, I just don't want government idiots mandating a certain piece of equipment before you can drive your car on the street. And emissions laws in NW Indiana (where I grew up) seem to be responsible for the scrapping of any number of perfectly operable vehicles, which as I understand it is bad for the environment. But anywhoo. /end{rant}