Exhausted
 

I am ready for the exhaust system on my 5.0L swap into a 1991 NA. I used the Martin Kit for the most part.

I see many custom exhaust systems out there but does anyone make any portions of the system that you can just buy and put together? I realize some fab work would be required but not starting from scratch would be great.

Who has experience with the Enthuzacar system? I realize it is for a LS swap but has anyone ever adapted it to a 5.0 application? Does its single muffler provide a sweet sound?

Thanks
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Indy 8

Meineke make up the four systems I've had made. Non cost me more than $1000 to have done. The only real "issue" is getting the car there as you really can't drive it with open headers (the noise is one reason, melting the front tires is another). What I've done is signed up with AAA a month or so ahead of time and had them tow it to the shop. The driver typically does not care what he's towing the car for as long as he gets paid. I usually just say the exhaust sort of just must have rotted and "fell off" which is why I now need the emergency tow to Meineke. Give the guy a $20 tip and he'll write whatever you want on the receipt.

I personally like the sound of two mufflers and a true dual system. Having it made this way also reduces the number of bends which allows the system to flow better which allows you use thinner tube (2.25) which in turn allow it to be tucked up higher. I went with 2.5 on my first build and say no loss when I went to 2.25. The headers are the choke point.

I used Borla ProXS mufflers on my last two builds. They are nice a quiet at idle but open up nicely at full tilt. To add a bit more drama at the track I'm having a set of 4 02 sensor bungs installed (two on each pipe, one in front of each cat and one behind) that I'll be able to uncap when I want a bit more "V8ness".

To answer the question that I'm sure a few are asking, exhaust cutouts do not pass inspection here in PA. As far as the great commonwealth is concerned, I'm having the o2 bungs welded in as "test ports" so I can test o2 levels before and after the cats while dyno testing. The fact that the plugs may just "fall out" during track days is a shame...

-Jason

Do you run an H or X pipe Jason?

Jerry I read a build thread a while back that the guy just bought a pile of pre bent tubes from Summit or someplace like that and did it himself. It didn't look very nice but got the job done.

I might just put some single chambers on and dump them at the wheels rather then fight getting around the 8.8 diff. That worked pretty well for Mr Shelby...

I used a universal 2 1/2" kit from Jegs. Also used their X type cross-over. Had to go from round to oval on the rear of the cross-over for clearance. Used some Magnaflow, full flow mufflers. They're loud, but the sound is music under load. Good luck with your exhaust. Let us know what muffler(s) you go with.

-Ray

I went with an H pipe. I think the crossover pipe itself is 1.75 or 2". I had a ball and socket joint installed in the center of the H so I can take each side of the exhaust down independently. Other than the collector flanges there are no other joints in the system. Getting it down and up is pretty easy (about 20 minutes a side) but it would be nice to have had a set of flanges further back so I could take just he back down if needed.

I went with the H based on the pictures that Martin has in his book and the recommendation of my exhaust guy. Since then I've done some research and it looks like H pipes are thought to sound a little better (more separation of the banks) but X pipes may give a little more low end torque and less tendency to create "drone".

-Jason

I went with a 2.5" system with x-pipe, high-flow cats, & Magnaflows. It sounds much different than my Mustang that has H-pipe, gutted cats, & Flowmasters, even though they have very similar engines.

How would you describe the difference in sound? I've felt the X-pipes I've heard sound more "blended" when the H pipes sound more "poppy". Do you concur?

-Jason

The H-pipe w/Flowmasters (American Thunder kit) are quite loud & have a drone sound at cruise speed. Flowmaster actually advises you to install an additional crossover pipe to "help" with the drone. The x-pipe design with the Magnaflows are not near as loud......until you get into the throttle, then they sound wicked. They have a sort of raspy, Indy-car sound, & seems to rev more freely.

I am running the Flowmaster American Thunder set up I took off my donor mustang. I used the x pipe with high flow cats and the flowmaster mufflers. It sounds great to me. Nice rumble at idle and sounds awesome when you get on it. However there still is somewhat of a drone at cruising speed.

On my LS set up I used a single Magnaflow dual in/out muffler. It is normally used in F-bodies. I have 2 1/2" pipe from the headers back and then the pipe is opened up to fit the 3" in and out. Dual pipes to resonated tips exit under the bumper. At first the sound was a little raspy off idle but the tips did a great job tuning that. I was actually surprised that a tip could do that in such a short space.
The car has a throaty growl and then uncorks to a pleasant roar when you hit it. It is not obnoxious and although it states its purpose, it wont get me in trouble with the Noise Police.

How do the F-body dual in dual out mufflers work? are they simply two in-out mufflers with the inlet/outlet on the same end welded back to back or does the flow actualy switch sides in the muffler (internal x-pipe)?

-Jason

Mine is a perforated X pipe inside the oval metal can. I have to say I really like the way it sounds. The car did have a rasp off idle as the two pipe came to an equalized presure but the resonated tips cured that. I have to say I am very impressed with Magnaflow's product. The Stainless tips I picked up off E-bay and they look and sound nice for the price ($29 each) They are 2.5" inlet with 3" outlet and a 3.5" outer shell and a rolled tip.

Jason 3rd and 4th gen F bodies all have a single pipe going over the axle into a single mufflier with 2 tail pipes. This is the exhaust out of my Camaro:
https://www.v8miata.net/attachment.p...ine=1363272375

Most factory systems send all the exhaust through the mufflier but this one is an SLP factory Boala system.

I dont know what GEN is what, but my friend has an 86 IROC with duals that has the same type of muffler as mine. Might not be stock but thats whats there.

3rd gen = 82 to 93, and 4th gen = 94 to 02.

Nope your friends is not stock. From the factory all F bodies went over the axle with a single pipe. I don't know much about Miatas but I do know GM Fs...:-)

I've got a question regarding the exhaust. What do you do about the lower rear body panel that's cutout for a single exiting exhaust tip if you are changing to dual exhaust?

Take a piece of paper and trace the original opening. Locate where the new opening will be, cover area with masking tape (I use blue painters tape). Mark the new opening on the tape, and cut carefully with a body saw or jig saw at slow speed (plastic tends to melt & look ugly if you run the saw speed too fast). Clean up the edge if needed. Good luck.

Or run a big fat single...

Jim, great pic! Did you have to go far to find that curve in the road? Looks like those are few and far between based on that photo! :)

How do you like your single exhaust sound on the open road? That's the direction I plan to take. I think if I ever ran duals, I'd have the LH outlet paired up with the pass side one - just inches apart.

LOL yeah that is the way everything looks where I live. The county I live in is so rural there is not a single stop light or 4 lane road in the county. I drive 34 miles one way to work with about a dozen 40 mph corners like that. I usually run 65 on the straights and bump it up to 85 on the curves.

The muffler is a Flyin Miata muffler 3" in and 3" out designed for their turbo systems. The only problem with it is it is way too quiet, for my tastes anyway... I have the system out now and am tweaking it to get closer to what my donor Camaro was.

I love that angry growl at full throttle! To be fair I have not opened up the Miata yet to see what it sounds like so I may not have that much work to do to get there. The headers on the Camaro were much larger but basically it was just a small internal resonator to cut the rasp and 10 feet of open pipe at full throttle. So most likely I'll put about a 2" cut out in the Miata just before the muffler for a nice big leak...