Gentlemen and Ladies if valid,
I have been off of the Forum for a while since my "Bertha" was away sitting at another location before I brought her back home. Anyhoo, she is a 1989 F150, 5-sped with 302. No modifications, no 4WD and may have a small lift (I am not sure if actual) but she sits higher than my '92 (could be the tires). Anyhoo, a few years ago i cracked the block and now i am finally getting back to putting another engine in her to get her back on the road. Like I mentioned, she is pretty stock and i really want to keep her that way for economic purposes. I have the manifolds that came off of my old engine and the replacement. I am debating whether to reinstall them or go with headers (probably shorties). My exhaust is pretty much shot from the cat back. They are in pieces and hanging on by wires. So I will be redoing it anyways. My cat goes into a single muffler; single entrance with dual exits. My dual pipes run toward the back right of the front tank, up and over the differential dropping before the rear tank and discharges to either side in front of the rear tires. I have uploaded pics for clarity. I love the set-up and want to go back with similar. My question is this, is it worth to install headers (I'm thinking of shorties) rather than the OEM manifolds? I am looking at a Flowmaster (Possible Magnaflow or other) Exhaust Kit that should mimic my set up. I haven't checked the actual diameters of my current exhaust, but i think will end up increasing to 3" pipes (worse case 2.5" i guess). I am trying not to have to replace the "Y" and cat; I think they may be alright. Again, i am not sure the increase in HP will be that much, thereby making it not worth the swap. Also, is there any other part of the system that will

dual pipes exiting the muffler and rising over the differential.

discharging to the side in front of the rear tire...both sides. As you can see it is not in its proper location, but i think you get it.
need to be upgraded to make this new exhaust system function properly?
Muffler exists looking toward the rear as it goes up and over the differential.

Piping exiting the muffler and dropping before the rear tank and exits to the side

Y-pipe to cat. Still in decent shape...

Piping broken at muffler from the Cat.

 

you will see almost no gain from shorties..the stock restricted head itself is going to be the bottle neck

 

So long tubes wouldn't help either without replacing the heads. I never really looked at going that route. I am not familiar with that so i don't even know where to start.

 

long tubes always help the most..but would likely only be a few horse..

years ago i installed a set of ford racing shorties on a stock internal 5.8..no real difference.
the stock heads can be massaged to make a difference, but im not a 5.0 expert at all. i just know that almost all 80s-90s fords dont respond with much when adding headers.
your truck looks to have a decent y-pipe merge, so maybe not much of a gain there either.

 

Yeah, I am thinking of leaving it as is as far as the head and manifold. I will still replace the the cat-back exhaust. But speaking of the Cat...if i was to replace it, does it really need the air tube? I was thinking of going with a spun body with no air tube. Or even a oval body with no air tube.

 

Put that & everything else about the truck into your signature as this page explains:

Well, the exhaust & coilover rear shocks are certainly modifications. I'd bet there are several more.That would be another mod - make sure that info is your signature, too.The closer you keep it to the way Ford designed & built it, the fewer problems you'll have, and the less money you'll waste.If economy & reliability are anywhere near the top of you list, you should certainly use OE or direct-replacement manifolds. I prefer to sandblast & paint them inside & out, and then install them with hi-temp silicone (instead of grease, like Ford did):

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What about it do you love? It looks pretty ratty to me, and I can't imagine that it sounds good with all the leaks & rattles.There won't be one - it'll actually DEcrease because it'll leak upstream of the HEGO, causing the engine to run rich.Every part of the engine system helps make the maximum output for the fuel consumption - from the WP pulley to the engine mounts & everything else. When you change something as significant as the exhaust, you should either calculate its impact on each aspect of engine operation, or just assume that it's going to be negative in many ways. Otherwise, just maintain it the way Ford built it - that's the easiest way to keep it running right without an engineering degree. All these run perfectly.

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I put everything in the signature that I KNOW of. I NOW know it may have some mods, but i have no idea what they were or are..
The coil over shocks and the exhaust was only a mentioned mod by Seve83. I don't know what coil over shocks are (neither the height of the lift if it has one). I thought it sat up high because of the large tires. As far as the exhaust, it was ratty as it began to fall apart. When I bought it back in 2008 it sounded pretty good, but i never looked at the piping. When i finally got around to it (after the pipe finally broke and I had to install a coupling and use coat hangers to hold it up) was the only time i really noticed all the leaks and rattling it actually had. I didn't do ANY mods myself. I am saying I like the set up in the way the exhaust is ran from the cat back (from the single entry muffler to dual exits), not the way it sounds all holy and falling apart. It is obvious that i need to replace the exhaust at a minimum from the cat back. I may go ahead a replace the cat, where it ties into a single pipe. I was just curious as to if upgrading (to shorties or long tubes) would actually be worth the cost and it sounds like it really isn't. I am not a high performance type guy, but i do want it to look, sound and run as efficient as possible as i will NEVER spend 50k on a vehicle. So last question, since there was a modification of the exhaust from a single pipe to dual pipes (with no performance upgrades of sorts like K&N filters and such), how much of a difference from the specs is it making (assuming all pipes, mufflers, cats, no leaks and placed sturdy)? I am assuming the pipes are about 2.25" and I have seen exhaust replacements up to 3", what would be affected?

 

Shock absorbers with coil springs fitted over them, to increase the net spring rate, and thus the ride height at a given weight.Then keep it as close to stock as possible. Direct-replacement exhaust manifolds, muffler, & tailpipe ARE possible.I'm not sure what you're asking - the amount of difference? There's 1 more tailpipe, so that's 1 different. The list of things affected depends on how detailed you want to be, but the important things (IMO) are the co$t, underhood temperature, noise, fuel economy, maintenance required to stop the leaks, extra weight on the truck, interference with other parts & systems...

 

Well i don't want to really upgrade from the way i bought it. Overall, it ran fine with no major issues that i could tell. I say major as there were a few minor issues as expected. I cracked the previous block but will be replacing it with a similar block with all of the other engine parts carefully placed back on. I have a stock '92 that i am parting out so my '89 will be pretty much back to stock. The upgrade in exhaust is really only a replacement of what was in it when i bought it; where the only UPGRADE may be in the diameter of the pipes by a 1/4". Sure it was still a modification from a single "in" to single "out" of the muffler, but I would think the fuel economy, temperatures, and weight won't be affected from where it is now. So when i am asking how much difference, i think it is minimal difference in all those things mentioned at best (fuel economy, weight, temperature, etc.). The noise will definitely be better (maybe quieter and consistent) since there won't be any leaks. I haven't seen any added parts from my truck to the '92 in the engine bay....yet... and i have been tinkering with both for a minute.