[Green78II]

I want to design a custom exhaust system for my 1978 Mustang II with 2.3L engine. I have a basic idea of what I want to do. I want to add a header, http://www.esslingeracing.com/mercha...egory_Code=HED Lose the catalytic convertor, (Exempt from emissions) and finish it off with either a side pipe http://www.pertronix.com/exhaust_pro...de_exhaust.htm or a 2.5" exhaust topped off with a warlock racing muffler. http://www.holley.com/data/products/...ockMuffler.jpg Comments/suggestions?

[74stang2togo]

Side-pipes are illegal in some areas, I'd check with the laws in your area first, also, a 3" exhaust is pretty excessive for a 2.3, even a 2" pipe with a glasspack can cause low-end torque problesm (trust me, I know this one first hand.)

A 2.3 side-exit exhaust (where only the tip is seen, these are legal in more areas) is suprisingly easy to do, I did mine with a glasspack, a handful of exhaust pipe clamps, a 90* bend, a hanger, and a tip. I simply used the factory headpipe with my factory manifold (it's ported, so it's got the flow I need for a combination as mild as mine, a dremel with the flex attachment and the harder grinding bits do much of what needs to be done on these manifolds). Doing one with a header will either be easier or more difficult depending on the nature of the header. If the header is long-tube style (exiting underneath the car and pointing straight back) it'll be easier, if it is a shorty style (exits near the motor mount or oil pan and points down) you either have to fabricate a head pipe or have one done for you.

As far as mufflers with a side-exit exhaust there are only two I can think of that'll give the ground clearance you'll need with a II (even with 16" wheels and 225/55 rubber mine's just barely high enough to drive it) one would be any glasspack, the other would be a Flowmaster Hushpower. Your muffler choice is going to have to be small to fit.

As far as the Warlock muffler goes, they're an excellent and durable design, just not very loud to those around you (at least, compared to most other Mustang exhausts, though the interior resonance is LOUD!!!) the flow is definitely great though, I picked up 3mpg on the highway with the Flowtech Stinger 2.5" system on my '87 Mustang 5.0 convertible, the Stinger uses non-bypass versions of the Warlock muffler with turndowns before the rear axle.

[Green78II]

Thank you for pointing out the issue with laws. In my state side pipes appear to be illegal (quick google search). As for a header, I'll probably go with one of the shorty pinto headers off of ebay. As you pointed out I'll need to get a downpipe fabricated for it if I can't salvage the original (header claims to bolt up to existing exhaust system). The rest of the system is toast. The cat was clogged with what looked like oil and the pipe from the cat to the muffler had a hole in it where it goes over the rear axle. Is the stock system 2 1/4" all the way back? I know thats the optimum pipe size for exhaust volocity for that engine size but I figured an extra 1/4 inch wouldn't hurt anything too much. Do I have to route the exhaust ove the axle or can I run it under the axle straight back? My car supposedly has a 2" suspension lift and stiffer springs on it so clearance shouldn't be an issue. I can crawl under it comfortably and still have room to work on the underbody without a lift or a jack. I want my exhaust to go: Header, Downpipe, Straight pipe(no bend for over axle) Muffler.

[74stang2togo]

My system was all 2" double-wall pipe from the factory, It's still all 2", but only the original head pipe remains. My exhaust tip exits about 5" ahead of the passenger-side rear tire and is loud as hell (not sure on the legality of it, but I rarely drive it during the daylight hours anyway) I've got an adapter on the end of it to run the rectangular Z/28 exhaust tip I'm using now (which is probably going to be replaced, the thing acts like a megaphone, without it it's much quieter) but other than that my whole system is 2" pipe, and I've got a 24 or 27 inch (can't remember right now) Thrush glasspack under it.