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There is a Flowmaster Series 50 dual-in dual-out 2.5" connections #8525554,lists for about $260. Moderate sound
Also there are 2 different Series 50 Big Block mufflers that have either 3" or 2-3/4" inlets that you can swell the pipes going into it to fit.
They are #530504 (3") and 527504 (2-3/4"). Both of these are quieter than the first one.
Thanks so much for the reply. I like that 2-3/4" Series 50 Big Block unit. I was also thinking I could neck down to 2.25" at the front of the muffler and use a 70 Series 524704 (dual in, dual out, all 2.25") and run 2.25" pipes over the axles and back to the (outer) two tips.
I'm going to get measurements today for this one. I'm pretty sure all this will fit. The car has a fairly long wheelbase, and it's a body on frame setup, like a full size truck or big SUV.
The owner likes to brag about the "Corvette engine" in this car and the overall Corvetteyness of the driveline. So, I'm going to give the owner two options.
The first will be a "basic" exhaust with 2 x flex couplers, a stamped X pipe, 2 x resonators (I've used the Vibrant ones and liked the results), the 527504 50 Series Big Block muffler and 2.5" over the axle pipes to the tips. Everything for that will be 2.5"
Diagram (not to scale, just a schematic view) of the basic exhaust option for this project
The second option will be a "Performance" exhaust which mimics the C6 NPP option. This will be the same at the front, back to the resonators, but with stamped Y pipes between the resonators and the muffler, a reducer at the muffler and the 70 Series 524704 muffler, 2.25" over the axle pipes back to the tips. The Y pipes will be vertical, tilted in a little at the top, and I'll run 2.5" dump pipes over top of the muffler, and between the main pipes from the muffler, then over the axle and out the back between the muffled pipe tips across the back, with some 3 bolt flanges for cutout valves right in front of the tips. I'll use an adjustable vacuum switch to control power for the electric operated cutouts, and open the dump pipes below about 5" vacuum (MAP over about 12 psi). I might even give him a "loud" switch (or button) on the dash in addition to the vacuum switch. Everything except the muffled tail section will be 2.5", with 2.25" for the muffled tail pipes.
Diagram of the "Performance exhaust" option for this project, with cutouts that bypass the muffler.
With either system, I'll probably use some butt joint band clamps (Walker "Mega Clamps" or equivalent) behind the muffler and in front of the X pipe to make it possible to remove the system in pieces in case repairs are needed, or the engine/transmission need to be removed (and I have to drop the cross member that's above the exhaust). We don't salt our roads down here, so rusty bolts or clamps aren't a big problem. And everything will be supported by adequate hangers. Hangers for the front section, from header to the flex couplers will be from brackets attached to the engine/transmission at the bell housing area, and 2 or three hangers for the main system, with a couple of hangers on the tail pipes section.
Last edited by Racer-X-; 11-01-2021 at 12:17 PM.
Reason: Added diagrams
I'm not sure there is much to be gained with the cutouts and their pipes but some more noise.
Also, with either of the quieter mufflers I mentioned, I don't really think you will need the resonators. Those mufflers are fairly quiet. Keep it simple!
I'm not sure there is much to be gained with the cutouts and their pipes but some more noise.
Also, with either of the quieter mufflers I mentioned, I don't really think you will need the resonators. Those mufflers are fairly quiet. Keep it simple!
Gains from the system with the cutouts are that it will be a little quieter because the capped pipes (when the cutouts are closed) are effectively two more different resonators in the system.
The added noise from the cutouts gives more Smiles per gallon. Plus the partner that signs my check likes the current system, which is obnoxiously loud and raspy. Right now, it's got two knock off short chambered mufflers that look about like 40 series or 44 series FlowMasters, but they are generic "house brand," maybe Summit or Jegs or possibly "blackhorse racing" from Amazon. The partner that doesn't sign my check thinks the current system is loud and obnoxious, an opinion shared by the other driver who has driven the car. So something that's both quiet (most of the time) and loud (sometimes) might be more politically feasible. I won't get into all the problems with the current "Built By Bubba™" system, but it has to go for a number of different reasons. We may be able to salvage and reuse the longer straight parts of the piping, but we've got to repair a dented/damaged gas tank that happened when the rear axle hit the pipe, and I've got to install a hydraulic power brake booster and a new master cylinder under the floor in the space where the driver's side pipe is right now. The current master cylinder is so close to the pipe that the rear brake line is actually pressed against the exhaust pipe.
2 sections do not slide on at all because of ends are either flattened or the same exact diameter. Both are off the muffler. Everything else slides on. Help. Advice. Please.
Pictures added to show. In full picture you see the 2 sections not joined up..
2 sections do not slide on at all because of ends are either flattened or the same exact diameter. Both are off the muffler. Everything else slides on. Help. Advice. Please.
Pictures added to show. In full picture you see the 2 sections not joined up..
That first pic shows a pipe that's clearly been damaged somewhere, either in shipping or at the warehouse where it was shipped from.
I'd get my "exhaust pipe expander" tool and stick it in the dented end of the pipe and push it back out straight. If you don't own an exhaust pipe expander, your FLAPS should have one in their "loaner tools" collection. O'Reilly stores usually have a couple choices for different diameter pipes. You pay the full price for a tool that's probably used, and you get all your money back when you return it.
Also, if a joint doesn't slip over like it's supposed to because both pipes are the same size, no difference in diameter, you can use that tool to enlarge the end of one of the pipes to make a slip joint.
Or, if you don't want to repair your "new" stuff, you could complain and send it back and hope they send you one that isn't damaged.
And for those joints, if you don't weld them, I strongly recommend a wide, dual bolt "band clamp" designed for lap joints/slip joints, like a Walker "MegaClamp." You might also need some exhaust sealant. I like the Walker branded ones because they have a blob of sealant where those clamps typically leak, you just peal the wax paper off the sealant, install it and clamp it down. Most of the time, the sealant provided on the clamp already is enough that it doesn't leak. With off brand "Amazon" clamps, you usually have to provide your own sealants, and some of those cheaper ones just leak no matter how hard you try to seal them up.
One of my pipes was like that. No pipe expander tool available near me so I put it in a vise and squeezed. Then used a mallet and a round metal dowel to re-shape it.
I still tack welded all the joints together because the clamps don't tighten down tight enough.
04-25-2016, 04:07 PM
