Has anyone ever installed a Donaldson M090535 so the inlet is facing the rear of the truck? I just got mine and it looks like it would flow way better the other way around. I have an M100465 on there that I modified but I lost HP/TQ with it but it looks like it would flow better than the 535 that I just got. Anyone dyno before and after the 535 install? Here is a before and after with the Flo Pro 5" straight through versus the M100465 on my truck. No other changes were made for the before and after other than the muffler swap. I have the cursor on the 70 MPH line because that's what speed I normally pull at. The drone is completely gone and it's much quiter but the loss in power is not acceptable so I'm going to try the 535 once I get my turbo back from HTT.

 

So everyone just blindly puts this stuff on and goes with it?????

 

I have not dyoed with the muffler off.. Just on.. So I have no comparison couldn't hack the loudness of a straight pipe??? But I am curious to your results when you put the new one on!!!

 

The loudness of the straight through wasn't bad until I tried to pull the toy hauler then you couldn't hear yourself think. I was just looking in the end of the new 535 I got today and it threw me the way the baffle looked. It seems you would have greater air speed if the inlet was turned towards the rear and so I was just wondering if anyone did that yet. Maybe I'll do it if I can't get my HP back with the 535.

 

yep that's what I did 5" straight is WAY TOO LOUD for me. I would take a 40HP loss if it meant I could think while towing
that being said when my truck was straight 5" I thought I felt no power loss on the low end....but when I put my 535 on last week it instantly felt stronger on the launch I am happy with it and so is the wife ....it's super deep sounding too

I too would like to see some before and after dyno's tho

 

When I got mine I second guessed the "inlet" arrow. It DOES look like it would flow better the other way. Mine sure isn't "quiet" the right way, so I'd imagine it sure isn't going to hurt the noise level to flip it backwards. If I had to do it over I'd probably run it backwards..

 

why dont you just flip it around??? did you weld yours in??

 

Yeah... The muffler is basically welded up so that it clamps to the downpipe, and then the tailpipe connects to it after a 12"(or so) welded on extension. I'd have to re-cut it up..

 

The old guy at the race engine shop I get my machining done at says that an exhaust that is too big for the exhaust flow will cost you alot of torque and a little hp. I kinda think he's right....The big sledpullers are making 1500hp or more through a 5 inch pipe through the hood...turbo, 90 degree and 2 feet of 5".... I think that the downpipe is where you can lose some power. If you have a 5" downpipe you had better be making 600hp. ks

 

i have to dissagree, i had a straight 4" mbrp dual setup then run a turbo back magnaflow 5" single now and truck guaranteed has more botom end and power. imo

 

When I went from 5" straight to the muffler it felt like there was more grunt added.... Not much but a little resistance may help...

 

What about the large Nelson, sorry cant remember the part number. Was 51 inches long straight through. I believe this is the one I want to get in the near future.

 

I agree 100%...

I have all the stock 4" down/tail pipe, but I wanted a hollow "crisp" sound so I went with the 5" muffler..

 

The old guys views were based on his experience with pulling tractors and semis....on the engine dyno. I'd like to see a dyno of a 450hp truck before and after a stock to 5" downpipe. His opinion was that the post turbo flow had to be tuned to the power you are making it to get the best torque...peak hp which is at high rpms doesn't change too much as by that time the rpm based pumping is strong enough to compensate for any restriction. The above dyno....not seat of pants seems to back the old guy up. ks

 

The peak HP on the graph is 607 and 595 respectively. I was pointing out the difference at 70 MPH which is the 444 versus the 393. Peak difference is only 12 HP but the mid range is around 51 HP loss with a more restrictive muffler. I expected it to be a gain in midrange with greater air speed (velocity) but a loss in peak because the torque curve should have "moved" to the lower end thereby not carrying the HP as high up the rev range as it did before the more restrictive muffler. It threw me for a loop and I still can't grasp why it happened the way it did. I have a Donaldson 535 to put on now and would like to see the difference but I'm afraid my new turbo may not give me the best comparison as too much will change to accurately test the theory because I will not have the HTB2 to compare with and I would be too lazy to just swap turbos back and forth.