anybody ever make one? I need to upgrade my exhaust and LT headers are just not going to do it, the car sits too low and i can afford to loose any more ground clearance.

Im currently building a 4" exhaust in the factory location, except the muffler is going where the cat should be and the tail pipe will be on the passengerside out the rear with a turn down.

Now, i have a set of SLP's craptastic shorties and y-pipe. Im planning to remove the y-pipe and heave it in the trash, cut the collector's off and have the tubing expanded to 3", i think it can be done, if not, i'll just have to cut them back a little further where it is wider and add a new 3" collector.

I think the passenger side will be ok as far as routing, as for the driverside, i dont have the room in the stock location between the pan and k-member for a 2.5" pipe let alone a 3" one. Im probably going to notch the k-member back a little and weld a plate back in to cove the hole.

I think this will work, it will take a little while to do, and im going to have to have the headers stripped and re-coated when im done, maybe fix the dents i installed so clear the plugs .


So, like i said before, anybody do this, ideas? pics? And please don't tell me i have to use LT's because its just not going to happen, i dont really care if im loosing a little power because of it, i just dont have the room.

 

I just took off my 4" Mufflex system. It runs exactly as the OEM system does, except it has a single outlet on the drivers side out of the Spin Tech muffler. It is actually a cat back that necks down to 3" at the cat to bolt onto the OEM or equivalent cat converter.

Honestly, I'm going to a true dual system because I'm just insane and like to make my life difficult. I think upgrading your system to 1 3/4 headers like Dyno Don makes would be the smart thing to do in your case, as they already come with larger collectors and "y" pipe than the SLP's. I don't think the 4" pipes afterwards is really going to do much for you, but if anyone is in the market for a 4" Mufflex Cat-back, PM me.

TA

 

Do all the mufflex's neck down to 3 inches for the cat, because if they do, I might have to do something else!

 

86, i dont know if anyone makes a 4" y-pipe, but i would say either build it yourself, or get a shop to do it. I got a shop to build my 3" mandrel bent y-pipe, they cut corners, and made it crush bent, and its more of a T-pipe than a y-pipe... It ended up costing the same as if i had just bought a 3" y-pipe.

Obviously youd save way more. if you can weld (and seeing you fab skills, id just go that route).

A few probs, i KNOW you will run into, are as follows.

You will have a hell of a time trying get the 90* bends in, after the header flange. The one on the driver side is not so bad, but the one on the passenger side will give you trouble. Notching the K member a bit is prolly your best bet.

I think it would be smarter to run 2 pipes and have them converge into a Y at the factory cat location, theres some room to work there, but making it converge before that is almost impossible without making it a T.

I also think you will run into probs running a 4" pipe under the oil pan, and between the crossmember. Even My 3" looks like a tight fit...

You might have better luck wth a 3.5" y-pipe and 4" after the y.

In any case, i definately think you should just fab one up yourself.
----------
Edit:

I just realized you want to do 3" y-pipe to 4" after y-pipe.... I got confused by the title a bit.

In that case, i would pick up a "Y-collecter" from jegs or summit, and construct the whole Y-pipe yourself. And then go with a 4" behind the Y. Have you considered Oval tubing? You might get more of a cross section than 4" and still have ground clearance.

 

Uh, how can you otherwise connect a 4" pipe to a 3" catalytic converter or Y pipe?

I searched everywhere and nobody makes a 4" catalytic converter or a 4" "y" pipe either, so it HAS to neck down to bolt or weld onto ANYTHING. Mufflex did offer to fabricate a 4" Y pipe if I drove the car to New Jersey, but you're still stuck with a 3" cat converter, so it's pretty pointless. If you're not running a cat, the 4" "Y" pipe will still have to be custom fabricated, so making it 4 inches longer to eliminate the slip-on reducer would not exactly be a challenge at that point.

So forgive me for saying your statement deserves a

TA

 

How much power are you going to make. A 3 inch y pipe is probably good for around 700ish hp. Unless your going to make more than that a 2.5 y is good for around 520 ish hp. Unless your going to be making big power don't mess with a 3 inch y much likely a 4 inch.my

 

Just food for thought here. Why not just buy a build your own header kit from summit with 1.75" or 2" primaries. I don't know what done to your motor but a 408 should easily make 500+hp with a good head and cam package. So I would lean toward a 1 7/8" primary if i could. I know there are kits out there that are basically a bunch of mandrel bent tubes in a box, but price I have no idea. I would start fresh though and build your own exhaust system using a header fab kit and them something like a you fit kit from flowmaster. It would probably be easier then trying to modify what you have and you could sell the old parts to recoup some cash.

 

Are we talking rear wheel HP, flywheel HP, crank HP or the elusive Internet HP?

TA

 

seems to be a little confusion. Im NOT planning to run a 4" pipe under the oil pan. It would be a 3" pipe from each collector, merging together in about the stock location (i think i have a clever way to do that) then to a 4" where it turns inward toward the cat.
I need to finish the rear of the car, so i can jack up the front and measure, but this is what im thinking about doing for the dual 3" to 4" merge. I want to run the 4" around and up to where the passengerside collector is, drop down with a short radius 90 and blend it into the tapered part of a 3x4 reducer, then bring the driverside pipe straight into he end of the reducer. It works great in my head, i just have to look under the car and see if it will work there.


I finished mocking up the muffler, intermediate pipe and over avle pipe tonight and welded it all together. So far (fingers crossed) it fits under the car VERY well, better than my flowmaster kit did, though it is a little close to the floor, might have to wrap it in a spot or two. I have to make the tailpipe section tommorow if i have time, the fab up a couple hangers, paint it, and im ready to roll, minus a filler neck for my gas tank

I will grab pics tommorow.

To answer some other questions, the 408 makes 501 hp and 520 ft/lbs at the flywheel, its a mild cam at the moment and has very good street manners, and once my funds regroup after this "gas tank swap turned into a complete fuel system and exhaust" project, im planning to delv into the motor, have the heads ported and do a cam swap. I have no doubt that this car will have the need for this exhaust at some point.

Headers, i would like to use what i have just because i have them, I was playing with the idea of making a set of headers, it would be a really cool winter project, but i think it would be a very difficult job just making them so that i can remove them when im finished. Maybe i will go that route, who knows, i do tend to go overboard with some of my projects. I found 1 3/4 header tubing kits, with no collectors or flanges for under 300 bux, so i assume 1 7/8 would be just a hair over 300
Hows this for overthinking a project, i was running through my head what it would take to convert the car to a drysump, then with extra room under the oil pan, make a set of LT headers, a standard style one for the passengerside, and a funky one that wraps under the pan and merge on the passengerside like some circle/dirt track headers setups. Now thats a mess of a project that i can see myself undertaking

Mufflex, i know of their kits, however im not going to spend 700 bux on something i can make for 350, besides, after swapping my fuel tank, i lost some clearance in the rear and the muffler would have to sit lower and everything would have to be tweaked and blah blah blah, so its just easies to just make it as i need it.

After seeing my new muffler, i think it might be loud, very loud...
----------
Internet HP? oh, i have about 1000 of those, just need to get some larger muffler bearings to harness the full potential

 

I'm at a loss for why you guys think you need something so big.

We have a 406 with this system making 403/439 to the rear wheels.

That's 2 21/2" into a 3" with 1 3/4" shortys and a 3" cat back.

 

i know i've seen a car or two putting down around 500 horse through a 3" catback, so i know they are good for a decent amount of power. Im more looking to the future of this car, the HP bug is not something that releases easily and im probably going to end up with a significant amount of power in thei car down the road.

And I just look for absurd projects like this for the winter months.

One question for you don, while your here, what size are the collectors on yoiu headers? 2.5" i assume? or larger?

 

They're not cheap but random technologies makes a 4" in 4" out bullet style converter

 

I think magnaflow makes a 3.5" in dual 2.5" out. That might be a good muffler for a 3.5" single system in the stock location, but it doesn't sound like you want something like that.

 

lol i just bought a fabbed up 3" into 4" then back into 3" Y pipe from a member here with hooker 2460 shorties. I just needed the shorties but i got the y pipe too. havent looked at it yet, still packaged up, but it looks decent in the pics

Its not hard to fabricate tho. Get a 3" into 4" splitter like the flowmaster y pipe and run 3" pipes down to it.



I actually may not even use this as i just needed a cross over pipe and i'll probly use 2.5" anyway.

 

I stand corrected, but they were not making them when I put my system on a year and a half ago.

TA

 

orrz!!! thats for the pic, that exactly what i need to make!!!!!

 

do you want it? PM ME