I have also gone with the Dynomax Ultra flow and love the sound. My next mod is my "Y" pipe. Could you tell me which one you went with and hat size. My muffler is 3" in 3" out.
The head pipe from the cat is 2.5".
Did your "Y" pipe mount right up to the cat or did you have to modify it? Also my O2 sensor is located right in the middle of my factory "Y" Does the new one have a position for it or do you have to move it or make a place for it. Please help!!!
Thanks

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97' F150 XLT SC ORP Flareside 4.6L Auto, 3.55 gears No LS,
Full power
Rear slider
Current mods:
Superchip Flipchip
K&N filter
Dynomax Ultra flow SI/SO
Access tonneau cover
Ford Bedliner
Vent visors front & rear, and bugshield
Ford Slush Mats
Kelly Safari AWR stock size tires
Mods to come:
"Y" pipe
WMS velocity tube

 

2winturbo- I love the sound too. My Y-pipe is the Flowmaster P# Y250300A. It has 2)2.5" ins and 1)3" out. My catback utilizes all 3" pipe, so the new Y-pipe's 3" exit runs right into all 3" pipe/muffler from there back. It requires custom installation/modification on all 3 joints. The driver's side pipe is cut off before it hits the OEM Y-pipe and a 90 degree pipe added to curve it backward into one entrance. I provided a mandrel bent 90 degree curve to my shop, as few shops have mandrel presses (I ordered mine from J.C.Whitney). The passenger's side pipe is cut off with a saw as close to the OEM Y-pipe as possible; this provides approximately 3" of pipe behind the oxygen sensor to work with (all of my sensors are in the original location). I removed my oxygen sensor for the joint that was welded within this 3", then put in back afterwards. After these 2 ins are fabricated, you simply make a 3" pipe that will go from the Y-pipe exit to the intermediate pipe. If I can be of any help, don't hesitate to ask !!

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2000 F-150 XL, RC, LB, 5.4L, 4R70W, 4.10LS,
Class III tow, Payload #3, & Convenience pkgs.,
4-wheel disc/ABS, Chestnut/Parchment 40/60,
Ford bedliner w/Paintsaver & gas/wheel/spare locks,
K&N F.I.P.K. w/Outwears pre-filter, Superchip,
Dynomax ultra-flow welded 3" cat-back w/ 3" Y-pipe,
Hellwig front & rear anti-sway bars, Rancho RS 9000s,
Pirelli Scorpion Zero 275/60/16s, Mobil 1, K&N oil filter.

 

I asked this question on another thread a little while ago and got no response, so here it is again. Does anyone out there have some good pics of this mod?? I have seen the pics from the "nice little 4.6 exhaust mod" thread. It doesn't really look like they used the Flowmaster type of 'Y' collector. It appears to be more of a custom fabricated piece. It also looks like the drivers side part of the 'Y' was re-routed behind the torsion bar cross member. Is this the way that you guys who have done this mod routed the pipes?? I looked at the stock 'Y' pipe in my SCrew and what a POS. I want to do this mod with a FM 50 but would just like to see a couple of examples, maybe even print the pics to show the shop.

Also, Max, did you have any problems with removing and replacing the O2 sensor. I've heard of a couple people having problems with the truck not running properly after messing with the sensor. Thanks in advance.

 

I will have to look into a little further and cantact my mech. to see what he knows. I wil definetly being doing it, I just want it to go as smooth as possible. Also I dont want any emission hassels. either. I will keep you posted. Is this the best way to contact you for info. Also I would really appreciate it if you had any pics of your mod. not sure how similar our trucks are but the more info. the better.
Thanks again,

 

GSCrew- I don't have pics. The "nice little mod" pics are of a Magnaflow Y-pipe, if I'm not mistaken. The driver's side pipe is turned back 90 degrees because the entrance to the new Y-pipe is a different angle. Not only is the flow engineering of the OEM Y-pipe pitiful, but it also doesn't do anyone any good to be running larger pipe behind it. The forward restriction of the single 2.5" exit limits everything from there back. Removing and reinstalling the oxygen sensor is only to protect it from welding nearby. It is returned to it's original position and causes no problems. This whole Y-pipe frenzy is funny; I was suggesting this over a year ago when I replaced mine, only a few people even understood it. I've had no problems whatsoever in that time.

2winturbo- You're welcome, you can find me here. Emissions wise, it's illegal in my opinion, which is the same as the EPAs Clean Air Act. Just like duals, it's illegal to modify the entire pipe segment that contains the cats; which is from the exhaust manifold to the first joint behind the Y-pipe. I've posted that link a dozen times with only negative responses.