exhaust system

OK-

Now that I've got the ol' firing order figured out it's time to start thinking about replacing exhaust parts. I read through a lot of the archived posts, but there seems to be mixed sentiment toward some things.

First, do exhaust mods hurt an otherwise stock motor? I have other mods planned but would like to put new plumbing on because it's pretty easy and gives me that sound I'm looking for.

Second, if I have to do one part (cat-back, h-pipe, headers) at a time, in what order should I replace? I recall Mr. 5.0 saying back to front but have seen conflicting opinions as well.

Third, are Motorsport unequal-length headers a pretty good compromise between performance and ease of maintenance?

Last, is getting the h-pipe off really as much of a b***h as everyone says?

Many thanks all...




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Greg
91 LX Convertible

[84_GT350]

As long as you keep the system at a reasonable size (no bigger than 2 1/2") you should be ok on a stock motor. You might lose a tiny bit of low end torque but it will be made up with the future mods you're planning. You're right about the back to front planning....that's how I'd have done it if I hadn't needed an entire exhaust system in a hurry. Get the mufflers and H-pipe at once. You'll want 2 1/2" mufflers, which won't fit on a stock 2 1/4" H-pipe. On the flipside, if you get a 2 1/2" H-pipe, the stock 2 1/4" mufflers won't work.

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1984 1/2 GT350 (#842 Hatchback w/ T-tops), 302HO, Comp cams Xtreme Energy cam, Carter 625cfm carb, Weiand Stealth intake, 1 5/8" MAC unequal shorties, 2 1/2" MAC Prochamber H-pipe, Flowmaster 2 chambers, KYBs, 16"x8" 4 lug Cobra Rs, Falken 245/45ZR16s

Hmmmm...

I don't know why, but I guess I thought a 2.5" Flowmaster system would bolt on to a stock H-pipe. Thanks for advising me to hold off on disassembly until I have the new H-pipe as well.

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Greg
91 LX Convertible

[NOS_Notch]

My motor is completely stock and i go 13.20's w/ 4.10's
I use 1 5/8" mac long tubes
2 1/2" off road h-pipe
2 1/2" flowmaster cat back
I believe there is no other way to go.
The hassle of the long tubes is worth the extra gain.
But if you chose shorty's go w/ equal length.
I had motorsport unequals on my old car and wasn't impressed.
I would do headers first.
piece together the rest, and do it at the same time.
much easier.
the h-pipe is a ***** along w/ the o2 sensors. plan on getting new, and make sure you have some good swivel pieces for your sockets(air tools would be great)



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4.10's,long tubes & 75 shot...Goes 12.50's
Check it out at http://www.burnouts.webprovider.com

[LX XLR8R]

def go MAC long tubes with no cat h-pipe and MAC catback exhaust..it will give you a nice sound and some power increase and get ur ready to build ur motor..o and hpipe ist hard to begin with but your will thank urself when you putting on a long tube h-pipe on..its cake

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1987 black notch(ex 4 banger)
DSS 306 w/ main support...Elderbrock 6028 heads..gt-40 intake..24# injectors...70 mm tb..77 pro-m...accel 300+..mac full legnth..tremec w/ pro5oh...full MAC exhaust,off road h-pipe,long tubes, catback...ron davis radiator..subframes, control arms...CFDF II..o yea holley FPR sucks..dont buy one..

[Jaydee]

For what its worth on my 87 LX notch, I bolted up a pair of 2 1/2" 2 chamber Flows to my stock h-pipe with no problem. I have added a 2 1/2" Mac high flow cat h-pipe since - fit fine with no problems.

I'd like to go with an off-road H-pipe but unfortunately I have California smog laws to deal with. Not sure if long tubes are legal, I'll have to check into that.

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Greg
91 LX Convertible

[cojonepony]

Being from Jersey I had to be concerned about emissions as well. I went with the Motorsport 1-5/8" unequals, a MAC hi-flo H-pipe (w/cats), and DynoMax UltraFlo catback. I changed everything at the same time rather than putting stuff on and taking it back off later. Removing the stock H-pipe wasn't to terrible and I bought new O2 sensors for the hi-flo H-pipe. The factory H-pipe is a bit cumbersome and I put 2X4's under it before I fully loosened it just as a precaution since I was working alone under the car which I had up on jackstands. The MAC H-pipe was easy to put in because its actually two separate pieces that get clamped together at the crossover (H) portion. I found that the DynoMax setup fit well also and the pipes lined up well. All in all its worth the effort for the sound and the Performance!

[AxemanZZ]

My motor is completely stock and I went against a lot of opinions that I would lose tons of low end torque if I went with 1 5/8" long tubes. I'd have to say they were pretty far off because I don't think I lost much, if any, and gained all kinds of top end which would have more than made up for any low-end loss that occured. I would highly recommend a set for your steed as well. They are sweet.

I would also suggest that you consider a complete exhaust system from front to back. If you have to buy one part at a time then so be it. Just install it all at once. This also makes the removal of the old exhaust easier because you can just use a sawzall to cut all the old stuff out and not have to unbolt anything except the headers. Your decision, but my exhaust was a piece of cake to remove and install since I didn't have to try to break all those #%$@ bolts loose.

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90 Mustang LX 5.0
My Ride*My Site

[Mr 5 0]

Mr. 5.0 still recommends front-to-back exhaust replacement and all at once, if possible for ease of installation and time savings.

Installing just mufflers and tailpipes does little for performance, but swapping out the factory headers and most importantly, replacing the factory cats with an 'off-road' H or X pipe or at least some low-restriction cats is a performance-enhancing modification.

If I could only do one thing at a time to my exhaust and didn't want to wait and just assemble parts, I would replace the factory cats first, replace the mufflers and pipes next and add headers, last.
Headers are expensive and can be difficult to install.
You need to know what kind of heads or other engine mods you are seriously planning on adding (not just dreaming about) to help you determine the right size, brand and (most important) type of headers to buy.
An H-pipe, hi-po mufflers and bigger pipes won't hurt anything but the wrong headers can be an expensive mistake.

Well, as always, thanks everyone for your good advice.

To answer your question about my plans, Mr 5.0, they are to build the car as a very strong street car - but nothing too radical at this point. I plan to add pullies, gears, cobra/gt40/edel performer intake, edel/gt40/windsor jr. heads, e-cam or equivalent...stuff like that. Then some suspension and brake stuff to round out the package.

No plans in the works for a power adder or more radical engine mods at this point. Maybe after I finish paying off the car and buy something else for commuting this will change - I can't say. If I were to build a Stang for racing it would be an LX notch or hatch. I have reservations about racing a convertible.



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Greg
91 LX Convertible