Thoughts on exhaust...

tbirdsc35th

Registered User
George, if you catch this, I just did a search on "dual exhaust" to see what came up and I found the post where you show a pic of your exhaust. that is beautiful. I think about this often and keep hitting that "keep it stock" voice when it comes to the 35th. Because of the age and mileage I will at least put a new original setup on it. But I see what you mean about the later model tank being more accomodating to dual exhaust. I assume the heat buildup isn't bad there at the tank. If anyone has any suggestions about mufflers and resonators, I would welcome the input. I don't want a loud car but I am wondering about opening up the exhaust somewhat to at least raise the torgue band in the RPM range. I have MORE than enough low end torque and would like some better mid and top range torque for freeway driving. Anyway that's just some thoughts.

A great week all.
 
Lance,
Just to make you feel better about cutting the original off, remember that you can tell them to cut it cleanly into sections and keep it. It can be welded back up later if you want it reinstalled for one reason or another.
I got the Flowmaster setup. It's not as effective as the SCP setup, but I like it. It's not loud at idle or cruising speeds. I figured that I can always swap the mufflers later if I don't like them, the main thing was to get rid of the resonator and the notchy bends. It does open up the piping some too, just not as much as the SCP. You won't have to swap your tank for it either, I just want to keep it as close to stock as possible, or easily reversible mod's.
 
Hi, Bill.

Thanks for that. I may be dreamin' but your direction is where I was hoping to go. When I helped remove the entire exhaust from my neighbor's 35th to remove the tranny, I liked the way the exhaust came out in two sections. It seemed possible to just have the rear section redone to do what I wanted to do. So the main thing is to not have the resonator at all, and then flowmasters for the mufflers? What do I get, just Flowmasters for a 90 supercoupe? I have a muffler guy close by that is a wizard in bending and shaping tubes and we could just use the existing hangers to mount it.
 
Lance,

Unfortunately, I haven't had an opportunity to get any pics taken with the car up on a hoist as of yet, so I can't show you the system via pictures.

When I did my HG's last January/February, I installed a set of ported stock exhaust manifolds. A few months back, I had a local exhaust shop install a custom true-dual set up all done in 409 Stainless Steel. It's all 2.5" tubing, including the downtubes. I've got a pair of 2.5" high-flow stainless cats. There's a 2.5" in/out stainless X-pipe located aft of the cats. I'm running a pair of the Borla 40665 mufflers, just like George Davenport. The system seems to flow very well, and I don't have a problem with droning despite not having a resonator. The enormous size of the Borla mufflers compensates for the absence of the resonator(s), I think. The sound is aggressive, yet not overpowering. I can still hear my stock blower (with MAC CAI) over the exhaust under heavy boost!

This system does require the swap of gas tanks, and I handled that at the same time that I installed a Walbro 255 lph FI fuel pump.

I'll have to see if I can't get some sound clips somehow.

Cheers,

Sean
 
Lance,
Just to be sure we're on the same page,
The Flowmaster uses 2 kit's: the 17100 which is everything behind the resonator, which is 2 in and 1 out, where it connects to the rest of the system. The resonator body is about 24" long, which is pretty long. If you wanted to leave off the resonator entirely or have your guy put in a different one, it would be no big deal not to get the resonator kit (#15100) from Flowmaster. I'd recommend this resonator though, I think that's the key to this thing having a more subdued sound. I have pictures at home of each if you want me to post. The center pipe is the main thing, to me, since I couldn't find anyone to do a mandrel bend. Ours ('89-91)have a really sharp bend under the gas tank. When mine was cut out, I got a good look at that stock pipe. Not a mandrel bend and it's pretty kinked up in several places. It was kind of funny looking that it was necked down a little in many spots. I kept the rear part from the Y pipe to the original mufflers. The guy cut it off before the Y and then cut off one side pipe to a muffler so I have it in 2 pieces (and it fit in the trunk). The rest I decided not to keep since it was just piping and really doesn't look worth keeping. The Flowmaster set has some odd mufflers, with a side entrance (I have a pic). That's why I kept the original, in case I wanted that Y pipe to tack on some other mufflers. Turns out that I really like it the way it is. Reasonable difference, didn't really lose any low end torque, but probably didn't gain as much as the SCP setup would have overall. Nice sound, not obnoxious.

I think it might be worth going to your shop before a final decision. Ask him to do a test bend on a 3" pipe for that bend under the tank. See what it pinches it down to. It might not be any smaller than the Flowmaster setup (2.5") if you start with a 3" pipe? The Flowmaster setup has a reasonable price though. www.Summitracing.com was a bit cheaper in shipping than Jegs. I got 2nd day for about the rate of regular shipping at Jegs.
 
Wow, I appreciate the specifics and details, guys. That helps. I had wondered about the effect of leaving off the resonator because I want to have a quieter system versus a rumble. :) And again my hope is to move that torque up the rpm band a bit for highway driving too. I've saved these posts if you don't mind for me to refer to later. My muffler guy will know more about your thoughts than I would so thanks. Even when I dealt with Bosses and Shelbys, I tended to keep them stock in this area so exhaust is, just like stereos, not an area I know a lot about. I know those darn Tri-Y's on that Hertz I had gave me fits keeping the bolts tight. LOL

Have a great week all.
 
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