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1968 Mustang Coupe 289V8 4bbl carb/intake tri y header 2 1/4" dual exhaust 3.55
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looking at installing a new dual exhaust system on my 68 289 that i just recently put a set of tri y headers on, was wondering if anybody has had a good experience with kits from summit, flowmaster, etc. or if i should just look at having a local muffler shop install a custom system
 

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I used Magnaflow on my Mustang, and a Summit kit in another car, happy with both but I still took it to an exhaust place to have it welded.....the mandrel bends in a kit are much better than a crimped bend.....and most exhaust shops do not have a mandrel bender.
 

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The thing to understand about kits is that there is almost always some welding required. If cost and ease are your main concerns, take it to a shop and have them bend you a system. 98 times out of 100 reduced flow from non-mandrel bends will be insignificant. If you have a really high performance engine and want mandrel bends to get the most of out it, buy a kit and have a shop install it if you do not have the ability to weld.
 
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I have mandrel bent tail pipes and straight intermediates that fit just fine. I hope to add HiPo cast iron manifolds and mandrel down pipes with a balance tube in the future, just to finish the free-flowing system (yeah I kinda went backwards) and have room for improved torque and hp later on.
 

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I just ordered a 2" system with turbo muffs for my stock manifolds.

I dont like loud and my drivetrain is bone stock so a 2" crimp bend system is fine for me. Im installing it in the garage with the engine, tranny and rear end out of the car.
 

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It depends on what your local shop charges and what your skill level is. My local shop would probably run in $7-800 for a custom aluminized non mandrel bent system. For less than I can get a mandrel bent stainless system.
 

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I installed a Flowmaster #17282 kit, which is for a '67, but worked on my '66 as I wanted the turn down tips and not the straight back tips. It was installed from my full length headers back. A local muffler shop in my town installed it for $385.00. While the kit looks good and sounds great at idle, the drone at certain RPMs is not fun. I'll probably end up changing out the Super 44 mufflers eventually.
 

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I installed a Flowmaster #17282 kit, the drone at certain RPMs is not fun. I'll probably end up changing out the Super 44 mufflers eventually.
Exactly why I went with generic turbo muffs. this car is a driver and i want it to be as comfortable as possible.
 

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I just ordered a 2" system with turbo muffs for my stock manifolds.

I dont like loud and my drivetrain is bone stock so a 2" crimp bend system is fine for me. I'm installing it in the garage with the engine, tranny and rear end out of the car.
You have made a wise choice. For street driving, the 2" GT system is more than enough. The Motive system is a very good copy of the original system. Fits very well, typically if there's a problem, it is minor and can easily be aligned perfectly with just a push or pull.
I installed a Flowmaster #17282 kit, which is for a '67, but worked on my '66 as I wanted the turn down tips and not the straight back tips. It was installed from my full length headers back. A local muffler ship in my town installed it for $385.00. While the kit looks good and sounds great at idle, the drone at certain RPMs is not fun. I'll probably end up changing out the Super 44 mufflers eventually.
The Motive system I mentioned above has, like the factory system, resonators in the tailpipes. Ford used them to eliminate the drone you dislike.
 

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I had a mom and pop shop build a system from the tri-y's on back for 500 including mufflers (Flowmaster 40 knock-offs). He was able to tuck everything up real tight into the tunnel.
 

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This is a 1966 GT350H, with the original Tri-Ys, and Motive exhaust. The H pipe was cut and welded to the Tri-Ys.
Only slight modification was need, on the RH side. You can see discoloration where the pipe was heated.


763362
763363
 

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This is a 1966 GT350H, with the original Tri-Ys, and Motive exhaust. The H pipe was cut and welded to the Tri-Ys.
Only slight modification was need, on the RH side. You can see discoloration where the pipe was heated.


View attachment 763362 View attachment 763363
On a different thread I asked about choosding between HiPo manifold and Hedman shorty headers. Got some good advice there.
Now my question is what is the advantage of the "H" pipe. Is it necessary and if so why?? Do kits come with the "H" pipe? Is an "H" pipe used on both HiPo manifolds and headers or just headers?
 

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I am fortunate enough to have a muffler shop that does custom work, and have a bender. They did the 3 inch on my 65 with a H-pipe and Magnaflow, and I'll have them do a H-pipe on my 68.
 

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I wouldn't buy a kit from Summit or others unless you see the exact same thing from NPD or CJs with perfect reviews then you'll likely still need some custom work because of the headers. There are a dozen subtle bends needed in the right places or its craptastic!
You should buy the pieces from NPD, I dont think they make a kit though. Get the tailpipes, mufflers, intermediate pipe and H or X pipe and hangers, install it from rear to front and marvel as it all falls into place. then fab it or take it to a shop for the final pieces from the headers.
At least buy all the specific hangers to have or a shop will use whatever they have on hand to get you out the door.
 

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Now my question is what is the advantage of the "H" pipe. Is it necessary and if so why??
It isn't mandatory, but it is a good idea when trying to balance pressures in the two runs. On a micro-scale, a cylinder's exhaust stroke is pumped into the pipe, but the firing order dictates which cylinder dumps when. It isn't even between the two runs. The H helps to balance it, evening the backpressure.

...as I understand it.
 
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I installed a Flowmaster #17282 kit, which is for a '67, but worked on my '66 as I wanted the turn down tips and not the straight back tips. It was installed from my full length headers back. A local muffler shop in my town installed it for $385.00. While the kit looks good and sounds great at idle, the drone at certain RPMs is not fun. I'll probably end up changing out the Super 44 mufflers eventually.

Put in some resonators. I just did on my Magnaflow kit and it made a good amount of difference:


These are the ones I used, and they have the best ground clearance of any I could find:


 
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Back in the day when your choice was glasspacks or factory mufflers we found that a couple of pieces of straight 2 1/2" pipe going into a pair of Corvair Turbo mufflers that dumped right in front of the rear axle was the best damned exhaust you could put behind the windsor motor. No muss, no fuss, no muffler shops. Relatively easy diy install and Ohhhhh that sound! Of course this was back when you had to have your car inspected annually so we would have a set of tailpipes bent that went under the rear axle. No it was not really roadworthy but it did get us thru the annual inspection!

Nowadays the racecar exhaust is a little more refined using an x pipe and flowmasters with 3" pipe but Ohhhh that sound at full tilt!!
 

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65 Mustang Convertible, 289, 4 spd.
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looking at installing a new dual exhaust system on my 68 289 that i just recently put a set of tri y headers on, was wondering if anybody has had a good experience with kits from summit, flowmaster, etc. or if i should just look at having a local muffler shop install a custom system
I purchased a 2 1/2” SS Magnaflow system on the rebuilt 289 with tri-headers for my 65 convertible. The original ad on CJPP indicated it would fit a convertible without problems but with some welding. I figured I could hang most of the hardware and have a shop just do the fit up to the header pipes where the welding was required. When I went to install it CJ had changed the ad and stated modifications were needed for the convertible. I ended up taking it to a reputable shop (he had a 66 up on the lift when I went to talk to the guy) and he did the fit up for about $350. No way I could have done it. I ended up having to deal with emergency brake interference with the four speed but got those resolved.

System sounds great.
 
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