Y-Pipe to Mid-Pipe

[atlM35]

For those who have done a true cat-back:

What setup do you have?

I'm looking for a setup where the outlet of the y-pipe matches the diatmeter of the mid-pipe.
Most of the parts that I've come across so far have a smaller diameter for the inlet of the mid-pipe, which would be a bottle neck, causing more turbulent harm in the flow than good.
I'm even open to having the inlet of the mid pipe be larger in diameter than the outlet of the y-pipe, but not the other way around.
I might have to go custom on this.

[mexillis]

For which one of your M's?

[atlM35]

For the 45.
I don't plan on doing anything to the 35, it's my daily commuter and I just spent a good amount on tires and front shocks for it... the money I was going to use for an Uprev on the 45 and then some
The factory exhaust looks inadequate for the 45's displacement, so I'm looking for bolt-on exhaust parts before the tune.

[mexillis]

I think dean is the only one who bought a prefabbed y pipe from the Internet and hooked it up to the Megan set up. All the other m45's that I've seen went custom. I almost went with an h pipe when I did my custom set up but instead chose to go the x pipe route. If you want a true dual, don't get the y pipe and go custom all the way.

[DeanM45]

Yep, bought a pipe for a G37 with a 3" outlet to attach to the Megan mid pipe. You will have to make two pipes with O2 bungs (easy if you can weld, pipe bend is about 30 degrees depending on how high you want your exhaust to be off the ground) to attach to the manifolds as the 35/37 manifolds and Y pipe are completely different than a 45.

Pipe you must make (one for each side):


Y pipe:



2 1/2" inlet on each side with a 3" outlet at the end.

[ISman]

I am looking at replicating this set-up however, do you know if the bends on the megan racing 350z/G35 cat-delete pipes will match up with the bend necessary to fit onto the m45 (I will be modifying the flange on the megan racing pipes to match that of the m45 exhaust manifold flange)?

[DeanM45]

I would imagine it'd be close but since you say you'd have to modify them it'd probably be much less expensive so just get some bent pipe (you can get stainless pre bent pipe-mandrel-all over the internet), the flanges, and then some O2 bungs. How much are the Megan pipes?

[ISman]

the megan pipes are 165 MSRP so I suspect you could get them used or off ebay for approx. 130.

Also, I was thinking that this might work:

http://www.nissanraceshop.com/product/3 ... -exh02g005

Assuming the bend angles were correct and you replaced the exhaust manifold flanges.

[DeanM45]

$700 is REALLY expensive. Granted, I did the welding myself but I am into my pipe (complete Y pipe) for no more than $350. $130 for the pair of pipes would not be too bad but it'd still be cheaper to just get the bare pipe. You will still have to buy the flanges either way so the only savings are the O2 bungs (cheap, $8/each). The pipe I bought was $28. Then I had a buddy bend them and I welded them up. I had to get 4 flanges instead of only 2 and they were $15/each (stanless but you can use mild).

[ISman]

you may have already answered this but, what are the specs on the pipe: ID, OD, and length? I may just go that route and have an exhaust shop assemble it for me.

Are you getting any CEL's?

[DeanM45]

I ordered 6' of pipe, 2 1/2" ID. The length and diameter will depend on which Y pipe you ultimately choose.
No CEL. As long as the secondary O2 sensors are there you should not get a CEL. I used the O2 stand offs ("L" shaped pipe/bung) for ease of install and to prevent any potential CEL. If you use a standard bung (like stock) you may or may not get a CEL, I do not know.

[atlM35]

So the purpose of your extra pipe was for cat delete? I haven't had a chance to look, but if I wanted to keep the stock cats on the 45, would an aftermarket y-pipe fit as a direct replacement?
I noticed that some were advertised to fit both m35/m45 as if the oem y-pipe were the same for both.

[DeanM45]

No, the secondary cats are in different places on the M35 and M45. The aftermarket Y pipes that are out there fit the M35 with no problem--they bolt to the exhaust mid pipe on the M45 but there is a large gap between the end of the Y pipe and the stock header (primary cat is on the end of the header and not removable). The Y pipe bolts to the end of the secondary cats on the M35. The secondary cats on the M45 are further down in the stock Y pipe.