what is the most economical exhaust modification for otherwise stock SC?

[sizemoremk]

I am curious what I can do to my exaust that will be cheap enough for the wife to allow, and let me change to a 5 or 10 % OD pully...though I'm open to tips on the OD decision.

I assume the freer flowing would also help a little with mileage....help prevent HGs from blowing...and give maybe just a little extra horse power

Are these cats the type that can be removed and material remove from inside to free flow? Or are new downpipes the only way?

I have no emmsions requirements by the way...
How dificult is it to remove the exaust manifolds and port them abit??? Is it worth it???

Do the origional cats go bad? I would think they woul get clogged up after awhile...but I don't know whats in these particular cats...

I aint looking to do any performance mods, I just want to free it up a little, and I definatley don't want a rice burner sound, the stock sound is good enough for me.

Thans guys!

[SeafoodSC]

For your needs, I would have a shop bend a set of 2.25" downtubes w/ no cats or get some from one of the SC vendors. Yes you can grind off some material from the stock manifolds around the collector. I did this before I went with headers and I feel its worthwhile and MUCH cheaper than headers for a mild upgrade. You also really need to ditch the factory resonator and get a magnaflow or something similar. Or you could eliminate it altogether, but it may not sound all that great. Considering you are not too interested in huge HP, the rest of the system should suffice.

[XR7 Dave]

Our cats are ceramic brick style, and yes they can be gutted. They do go bad if the car has not been kept in proper tune, but they can also run 150K+ without replacement. Keep in mind that when gutted, the exhaust will sound "tingy" up front. A lot of people don't like the sound. If you want to remove the cats, I personally would have some downpipes made.

As for the first modification, I would lose the resonator. It will become only slightly louder, and test have shown that the resonator is very restrictive. That is your cheapest mod. The mufflers themselves are not that restrictive. If you remove the resonator AND cats, it will become pretty loud. Then you would need to put in a resonator. A good resonator will run you about $75-100 from Magnaflow.

I don't recommend any other brands. The Magnaflow 5x8 oval is a straight through, 2 into 1 and available in different lengths. I'd go for the longest one you can fit.

Exhaust mods tend to be expensive. Keep a couple things in mind. While somewhat small in diameter, the stock exhaust is not THAT bad, pipes wise, and they are made out of a mild grade of stainless steel. So think twice before you toss the stock pipes. The next set won't last as long. The cats are the most restrictive, followed by the resonator, then the mufflers. Neither the resonator or the mufflers are stainless and they tend to fall apart with age.

It would be usefull to open up the stock manifold collector to 2", but other than that, there isn't much to be done with the stock manifolds anyway. I wouldn't personally bother with porting the stock manifolds. When you are ready for headers, the MAC Mustang v-6 shortie headers fit with minimal modification and will flow many times better. They will however require custom downpipes.

[tbird88]

I'm a little busy right now but...

[sizemoremk]

Well I like my 90 stock, I want to keep it as original as posible, I have removed the air silencer, but I still have it in the garage...

As for headers.....I will not spend more than half the cars book value(I say this as it is plenty more valueable to me!) on one mod...500-600 for headers, and then another few hundred on the rest oif the exaust! The wife'd never go for that at all anyways. And it would also detract form my GUN COLLECTING too. (It has priority, as I want as many as possible before they are all illegal to buy...)

I see that the gutted cats will sound "tingy..." will the downpipes also sound tingy? Or does the ting come from remnants of the guts in the guted ones? I don't know why, but it just "feels" like the exhaust is a little restricted; in the sound and just kinda feels this way too, how canI tell when my cats are going? I mean the whole exaust system seems to be physically in-tact, but just feels like it needs to breath more.

Proposed solution:

So downtubes and a replacement resonator would't sound very much different, and most definately NOT sound like pissed off bumblebees? What size resonator can I use and stick with the remainder of the stock exaust?

As for the exaust manifold.... Is the collector the only thing I can port? I figured there'd be little more "meat" in the exaust port side that can be removed....If not can I assume a dremel tool and a trouble light and a while under the car will be OK for porting the collector whiel still on the car? Or will a die grinder be necessary and be done on a bench? Any before and after pics of what metal was removed?

Sound right?

On getting downtubes made, what diameter are they, and should I just carry my cats in to an exaust shop and have them made? What $$$ ballpark will I be in if having them made? I have seen them for sale by someone before on this site, are those recomended/still available?

[tbird88]

Originally posted by sizemoremk
Any before and after pics of what metal was removed?

Porting enlarges the ID of the collectors from 1-7/16" to 2".
Do them off the car.

'bird

[sizemoremk]

got the manifolds off while I'm doing motor mounts...I hope it's worth it...

Any votes on my proposed solution about downtubes and new resonator???

Where do I get the resonator, and is there a source for downtubes that may be cheaper then an exhaust shop?
If not, Maybe I should design my own set that can bolt up to the favorite resonator and get the shop to make a few that I can sell em to help pay for my SC projects...