I had 4" straight from the downpipe all the way out, exit in stock location. I cut out a section and added a 16" spark arrestor off of a 4-53 detroit, which is straight through but has about a six inch gap between the inlet and outlet. With the 4" straight, I could easily get to 32-34 lbs boost, now only 27 max with a slower spool up [img]/ubbthreads/images/graemlins/frown.gif[/img] I had no smoke, now rolls some black smoke. It is quieter, but I do not like the performance drop [img]/ubbthreads/images/graemlins/shrug.gif[/img](who would have thought)-I would rather have the noise! Guess I'll be looking for a magnaflow or aeroturbine or something, and I am tempted to call Dale I and ask about his 3" to 4" downpipe since I discovered how much this matters.
I believe it is from the turbelunce you introduced into the system. Having a gap in the piping will slow down the exhaust gases from exiting the system, similar to the crushed downpipe. The magnaflow is a nice piece, it is baffled instead of having a gap between the inlet and outlet, I went with one and am happy with it.
I bought a 5" Magnaflow & it necked down to 4" on the inside-sent it back.I liked mine w/out a muff,but tried one to see what it would sound like.Right now I'm using a big rig muff-it's like a glasspack,straight through,just louvers.I'm sure 4" is big enough, I just didn't want to run all that 5" pipe and go down to 4" at the muff.
Brian
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95 F350 CC XLT,bought new as 2x Dually,owner converted to 4x4,open intake,SD IC,1.0 Housing,Pedestal Mod,Gutted EBPV,dp,5"no muff, Baumann TCS controlled e4od,"I LOVE that thing"!,Baumann VB kit,UCC Custom Billet T/C-VERY low stall speed,Mag-Hytec pan,dual True-Cools,remote filter,3 pos.T/C lock-up switch w/LED,Elec.fans on trans.& engine w/Derale adj.stats,Gauges,Kingpin D60 w/Lock Right,Detroit Locker in the 10.25,4.88s,4" Nat. springs w/ORU-SRK in fr.,crossover steering,10" Atlas springs in rear-no blocks!,Bilstein 5100s,38" PJ Dirt Grips on 16x12" M/T Classic Locks w/Centramatic balancers,Warn hubs,Powerslot rotors,Hawk pads,Can-Back canvas top.
I am using a Walker glass pack, p/n 24217. It is stainless steel, 4" in/out, and about 20" long. I did not lose any power, and I spool up just fine. Its nice and silent while cruising, but sounds REAL nice when you step on it. It is the flow thru type wrapped in glass wool. I too tried various muffler assys. but all were too silent and/or reduced performance.
You probably don't want to run a muffler that utilizes a baffle. It will significantly reduce the available cfm flow. For instance:
4" in/out baffled: 1750cfm @8"H2O
4" in/out w/o baffle: 3200cfm @8"H2O
Of course, this may or may not be the measurement for the exact muffler you have. You will have to contact the manufacturer for their spec. But, even with a bit of variance you can still see the difference.
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Thanks for reading, Dale Pics 1995 F350 - To much stuff to list,
more money spent than I want to admit.
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