Now that my D1 is down for maintenance, I'd like to make her sound throatier and breathe better. Not concerned with drone. As long as it doesn't throw codes. Already have a cold air cone filter set aside. Looking at deleting the resonator (mid muffler) and replacing the actual muffler with a flowmaster 40 series or equivalent (super 44, thrush, dynomax). My question is what size tubing will I need for the resonator delete / how long and whats the muffler input size? Would save me some time and work if someone has the dimensions on hand. TIA

 

I'm leaning towards the flowmaster super 10 with no resonator.. Nice and loud.. Had one a few years back on a 85 Woody Grand Waggy I had and loved it. Cab drone wasn't bad at all. I actually had worse drone on my 85 K5 with Doug Thorley headers and a super 40. Any one have the ID's & OD's handy for the resonator and muffler? Thanks!

 

Well after some researching I found that the resonator is at the rear so all I'll need for that delete is a nice exhaust tip. As for the muffler size I believe it's 2.5 id / od. With the muffler sitting mid vehicle now, I think I will run a 40 series or equivalent instead if the throatier 10 series. I was under the impression that the middle muffler was the resonator (pre-muffler). Now that I'm Edumacated, I can begin shopping & chopping. Lol.

 

i'm running a magnaflow catback system. i got it second hand for the price of a cheap OEM muffler, so i couldn't say no. being in the northeast, those aluminized mufflers are junk and rot out in 2-3 years so i would get nothing cheaper than a flowmaster so its at least steel.

the magnaflow setup is 2.5" to the muffler (middle of the truck) and either 2.75" or 3" straight back after that.. no resonator. its sounds awesome but isn't by any means loud. my buddy's disco is 2.75" straight pipe (w/ cats) and even that isn't loud. it seems the cats really muffle the sound on these motors.

 

I deleted cats, removed the muffler and resonator at the rear, installed a thrush welded muffler( fake flow master)
We bought a new over axle pipe but you need to Fab cause unlike a USA truck rover makes part of the over axle pipe on the muffler to cost you $ when it goes bad

To delete the tailpipe Res just get a long tailpipe ext from parts store, pics and sizes are in my thread, its loud and drones but I have no cats, thrush welded is real nice but way cheaper then. Flow master

Save the front flange off old muffler weld to new, iirc it is a center inlet, offset outlet muffler

 

Directions from my thread page 16



Pics of the exhaust we made up
Buy a muffler with center inlet offset outlet and a piece of straight pipe to fit the inlet think we used 2.5"
Cut the flange off the OEM muffler weld onto your straight pipe
lay that and the new muffler side by side cut down the pipe to make the assembled pipe and muffler length same as the old muffler BE SURE THE FLANGE IS CLOCKED CORRECTLY BEFORE ANY PERMANENT ATTATCHING
We clamped this in case the pipe outlasts the muffler and I need to do it again this is the second time I rebuilt this exhaust since owning the Rover 4/5 years now

We bought a new over axle pipe amazon or ebay cheapest, 45* , straight pipe, universal turn down ( this goes in place of the rear resonator)

With muffler mounted install over the rear pipe making sure it is positioned where the upper A and axle will not hit we had a jackstand under the muffler and tacked on the over axle pipe

Then assemble the remaining pipes and attach the 45* to the over axle pipe and make length adjustments as needed so the tailpipe comes out in the proper location

Lastly remove and weld up then final assemble on vehicle, at this point you will need to weld a hanger at the front and rear of the muffler

We found the over axle pipe to be an odd size tubing, and the 45* is needed cause the over the axle is incomplete the last bend is part of the rear resonator

Wish I had pics from the process

 

Sweet. Thanks.

 

there are 2 or 3 pics on that page


2 biggest things seem that the flange on muffler is clocked right before welding and be sure you articulate the suspension to make sure the over axle does not hit the upper A arm iirc there is only so much room for error with the A arm area




my over axle pipe looked great but was rotted on the weld seam on top where you cannot see

 

***** it! Going with a flowmaster 10 series.... Lol. Mainly because I got one for $27 on eBay! Haha. Gonna get the engine overhaul/rebuild done first with the stock exhaust on then once I got her running right I'll weld this phucker in and delete the resonator.

 

I did some muffler sound testing on a bunch of different mufflers. I tried 3 flowmasters (including two-different chamber types and a Hushpower), Cherrybomb Vortex, Dynomax, VT etc. I recorded the sound so I could analyze it more objectively. I could both measure it, but more importantly, compare the sounds within a few seconds of each other.

I did not test a Magnaflow because it is internally the same as a Dynomax, just with a polished case. I did test the VT with the flapper valve that is supposed to reduce the drone on these types of mufflers. I did not test a Borla because I'm going to smash it offroad.

My test, and any person's results will be obscured significantly by the catalytic converters, especially if they're plugged. I actually drove a few blocks with no muffler at all before I could get everything welded, and it wasn't that loud because the cats suppressed the sound so much.

If a person wants deep tone and loud volume, I recommend addressing the cats, and using a Flowmaster 44. Nothing I tested was as deep-sounding as the 44.

Cherrybomb Vortex sounded very good, almost as deep and throaty as the 44, but it was built very poorly. The welds were an embarrassment with gobs of slag bigger than marbles. (Chinese manufacturing vs. Flowmaster's California factory... no comparison)

The Flowmaster 50, and the Hushpower (acquired by Flowmaster) had nice sounds at low volume.

The Dynomax mufflers use packing like a Magnaflow and they sound higher and are known for droning. The argument in favor of them is they flow freely without obstruction. But the advantage of this is often misconceived. First, we only need a muffler to flow so much before it is no longer limiting power. Even near that maximum flow rate that the engine can use, we're only using that near the engine's maximum flow near redline. That's not where I drive my 4x4.

We can talk a lot about what the exhaust could do to help bump torque up, but for me there is practically nothing I can do with the Discovery's exhaust. The hedmen headers that are out there will ruin torque for gain on the top end if you also work on the top-end. I'm not going to get custom made headers. I also can't do anything practical to shorten the collector length without losing ground clearance. There's just not a lot of practical options unless you go to extreme measures to modify the car. So the bottom line is we're going to pick a muffler based on the sound as they will all perform the same.

I tried the Dynomax VT thing, which does cut the droning, but has been reported by others to rattle at idle (really it's blowing open and leaking). For me it seemed to work fine but sounds just like any other packed straight-through muffler.

I'm not necessarily a fan of Flowmaster. They have a sound that is deep, but it is not unique. The Buick-derived Rover V8 has the same firing order as the small block Chevy. Paired with a Flowmaster it just doesn't sound unique, and it certainly doesn't sound British.

Ultimately I chose a combination that gave me the lowest volume level. If I were to look at this issue again, I would focus on Flowmaster and Hushpower. I think a 10 series by itself is the wrong way to go, but one or two could be used in combination with another muffler. The problem is the limited space.