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I was looking for more flow from my Coupe after hitting the dyno in the fall. We made around 280-290 whp with the stock coupe pipes and when we pulled them off and made some pulls it dynoed around 350 to the wheels. I needed some work done to the car so I sent it off to Mark Dougherty's Shop in Annville. The top of my list was the exhaust. I used my stock 351 hooker headers I had from FFR and I told mark I wanted to have the same dual pipe look and unique sound but with more flow. We were originally going to gut my pipes but it was not worth doing. He eventually decided to build me a new set. They look awesome, much more meaty compared to the old ones. Brian Z did an awesome job with all the welding, very clean. They sound mean too. Way more throaty and deep then the stock pipes. The car pulls more strongly all around too. I picked the car up Wednesday night and I had to drive to Charleston SC the next morning. Obviously I couldn't let the coupe sit there all weekend so I drove it all the way down. The pipes are awesome you can't get sick of that noise even after 1400 miles. I notice they sound especially good blowing the doors off a Prius while traveling "The Speed Limit" :D or while keeping the neighbors awake at 2am :001_tongue:

Big thanks to Mark D, Brendan D. And Brian Z.

 

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Gotta know what mufflers they are....drove mine about 100 miles today and I'm sick of the stock sidepipes again.
 

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ROOKIE!
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WOW! They look great! Post a video so we can hear please!
 

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Howdy Chris,

+1 to what everyone else said.

And.......


Well, more pics anyway. :)

I'm going to do "something" different with the exhaust on my Spyder and I would like to keep the twin sidepipe look and your's look great.

Paul
 

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Hi guys
here are a few pics of chris's car from the side.
The mufflers we used were Thrush Stainless Steel Glasspack Mufflers 24239 from summit 100 each. we used these so they would slide into the new 2 1/2 stainless pipes.
So to recap
stock FFR headers
4) 2" - 2 1/2" reducers
4) 2 1/2" stainless 30 deg. bends
4) thrush stainless mufflers
4) 2 1/2" stanless 90 deg bends

Some of the other upgrades done to chris's car for this season were.
remove leaking stock FFR rad and install Breeze auto roadster Rad. 30% larger. ( yes we had alot of fab to do for this) but as chris will attest well worth the work the car now sits on 75-80 cel. in stop and go traffic.
Fast freddies power steering pump with NAPA rack. allowing for a much better alighnment. WOW what a huge difference Chris has much more car control.

Borrowing from the roadster forum we installed the marine wipers in the coupe with a sync between the motors.
not as tuff as we thought considering he has A/C.
unbelievable.
Chris was in a 3 hr down pour on his way down south. with not a single hiccup from the wipers. and they now park.

This biggest pill to swallow was the scrapping of the Fast EZ EFI. After many hours on the phone with the techs from Fast and countless dollars spent on the dyno beating this thing to death. We all decided to just try a carb since we had tryed everything else. Holy sweet running coupe Bat Man. even though the carb is alittle small it ran incredable compared to before. It now pulls 5th gear, runs and idles smooth, And milage is up 40%.
who says old school is bad.

Dyno time soon to come but the butt dyno says we are way up. so I am hoping for 30- 40 hp at the wheel
well thats all for now.
later
mark D




Here is a rare Chris stiting in the background with Brian Z by the sidepipes.


 

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ROOKIE!
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Looks so good!
 

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Awesome! Love it!
 

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very nice!
 

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Howdy Mark,

stock FFR headers
4) 2" - 2 1/2" reducers
4) 2 1/2" stainless 30 deg. bends
4) thrush stainless mufflers
4) 2 1/2" stanless 90 deg bends

later
mark D
Where did you buy the rest of the parts listed?

Jegs has the mufflers on "special" for about $73.00 each.

Paul
 

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Please sell this as a upgrade!
 

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you can purchase everything from jegs or summit.


give us a call if you need them we seem to be making alot of custom exhaust systems lately.
Coupe duel pipes
coupe single pipes
roadster undercar
we do it all in stainless mandrel bends

later
Mark D
 

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Can someone add to my comparison between single and double chamber exhausts...for the coupe?

I would be interested in upgrading also but probably want to keep the headers.

Mark's Dual: closer to original look, able to use the stock FFR headers, glass pack section reduces loudness (until it get's blown out), still has some flow restriction

Mark's single: allows more flow, need new headers, maybe less decibels, not quite as original looking.

Mark, are you offering to make them or supply the pieces to make them?

Marc
 

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Mark,Very nice work! I'm buliding what I hope will be a pretty accurate replica of the originals. Thus, I'd like a longer "shell length" (the larger diameter section), as Thrush calls it, than the 24239. I see that the Thrush 24205 (one of the powder coated versions) has a shell length of 26", which is close to the 28 or so inches of the FFR side pipes. The problem is that the stated "through pipe" diameter is only 2", as opposed to the 2-1/4" that is claimed for the 24239 you specified. I looked into my stock FFR pipes and see that they have a 2" throuugh pipe, but it is further constricted by a lot of perforations, which maybe net 1-3/4" max. If I want to achieve much less back pressure than stock, in addition to the original look, do you think that the 2" through pipe diameter will be too small, compared to the 24239?
 

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I was running thru my research on exhaust system design and reacquired the article Dave Vizard wrote in 2009 for Popular Hot Rodding. One of his points about mufflers was specifically not worrying about the pipe diameter for more than simple mechanical fit up - what he recommended was knowing the CFM rating of flow and matching that. The byzantine wanderings of exhaust flow inside the muffler are hard to judge, it really just boils down to sizing it for that case just like a carburetor. It should be obvious that a muffler that flows too little will choke the system just as much as a carb can, and I completely agree there is far too little information available about flow rates of mufflers.

If there was any one area he cautioned about, it was going too big - that lost power or elevated noise more quickly than a slight undersize because of velocity loss and increased resonation from a larger than needed volume.

Anyway, FWIW: Auto Exhaust Science

Going back over it again, I'm prompted to reconsider undercar exhaust. The transmission cross tube is the only real obstacle, and it's a good place to locate the X pipe to minimize hacking it up.
 
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