I went to Stan's Headers to talk custom exhaust on my car.
They are the only place that makes up to 5" mandrel bent exhaust and the are a header manufacture.
I put the car on the lift and Stan wanted to look at it him self. I told him I wanted a custom Y-pipe like the one I had in the picture (Top Secret). His answer was "First I don't like to do one offs, they don't make money and We are manufactures of the custom systems we install and we sell those systems alll over the USA to people and shops for install."
I spent 2 hours with Stan talking about manufacturing a custom exhaust for our cars. we went into the header jig area where they make headers from scratch. He said "The Y-pipe in your picture isn't to good because the pipes need to run side by side for a couple inches before they actually merge, they probably did it the way because you can't really bend titanium. Look at the multiple pieces that are welded together for such a simple Y-pipe, they have to piece it together and can't make a real merge. That won't work with you stock system anyhow because the rest of your exhaust is too small."
So we measured the stock one: 2 X 2 1/8" out of cats. merged into one 2 3/8" all the way back to the muffler " and it's made out of 409 stainless steel from the factory".
He said two 2 1/8" pipes flow the same as one 3" and the factory Y-pipe is terrible.
He said "Take your car and Dyno it, then I'll make a new full mandrel bent 2 X 2 1/4" into 3" exhaust for your car for a prototype for you to Dyno. Then you make jigs from that so I can manufacture you exhausts systems to sell to others on the Internet.
He said "We can make them out of regular aluminized pipe or 409 stainless steel." I asked "Why 409 stainless everyone else uses 304 stainless steel?"
He answered"304 polishes up really nice but it crystallizes from heat cycling and gets brittle and cracks up, just won't last thats why the factories use 409 OEM. Kinda brown and doesn't polish but doesn't break and reliability is a must for the factory. The new emissions regs on exhaust say the have to work for over 100,000 miles from the factory. We can put 304 tips on it for looks and they will survive but any thing else forget it.
The 350z has different than standard size flanges at the cats, so I am cutting out new flanges for the prototype and will have info/pictures in the next month for all. If we get good dyno and sounds from it we start manufacturing.
Any body want one of these if they work?
Y- pipe back complete out of aluminized should be less than $700
409 Stainless steel should be under $1000 complete w/Y-pipe.
More R&D to follow.

I am kinda slow at getting done with all of my product development since I have a "real" job unrelated to cars that takes my time too.

Any questions/requests PM me.

 

I'd be interested if his system can produce decent results. The guy seems to know what he's talking about ... but then again, he's trying to sell a product. As for exhaust flow and his recommendation on metals... I don't know much about that... I'm sure others here will chime in.

I don't doubt his credibility, but I'll have to see some solid #s before a decision could be made. It's certainly got me interested. Keep us posted!

=iboost

 

I'm definitely interested in the Y-pipe.

 

The interest will be there if the results are. I like many others have money to burn, but want proof.

 

I did the numbers about the 2 2 1/8 inch pipes being equal for flow to a 3 inch and he is correct. I don't have info at home about 409 vs 304 but I suspect he is correct on that also.

 

Here's some info on 409 SST from the following website:

http://www.azom.com/Details.asp?ArticleID=969

One excerpt that I found interesting was the following (it was an html table looking thing, so not sure how it will format)

Possible Alternative Grades
Possible alternative grades to grade 409 stainless steels are given in table 5.

Table 5. Possible alternative grades to 409 grade stainless steel

Grade
Why it might be chosen instead of 409

3CR12
Similar corrosion resistance, easier welding and more readily available than 409, particularly in heavy sections. (409 may have better drawability than 3CR12.)

304
Better corrosion resistance and heat resistance but at higher cost.

321
Higher heat resistance than 409 or 304.

Aluminised steel
Lower resistance to exhaust gases, but at lower cost than stainless steel



OK, so it didn't format at all. Anyhow, it looks like the website is saying that 304 has better corrosion and heat resistance, but costs more.

Can you get some clarification from the shop as to why they believe differently?

-D'oh!


PS. I don't want to make it seems as though 409 isn't any good, so here is another excerpt from the site:

Background
409 is a titanium stabilised ferritic stainless steel. Although regarded as a general-purpose chromium stainless steel the primary application for Grade 409 is automotive exhaust systems. Its applications are those where appearance is a secondary consideration to mechanical properties and corrosion resistance and where some weldability is required.

More highly stabilised versions of 409 are useful where 409 has been proven marginal - these grades S40910, S40920 and S40930 are stabilised with titanium, niobium or both titanium and niobium.



-D!

 

Stan said that the 304 stainless got brittle and cracked from heat cycles. He said that 304 was considered a better stainless but because of the embrittlement it was a problem in exhaust pipe thicknesses and he did use 304 on the 3/8" flanges he uses because 409 is not really available in plate form.
I'm not sure if the info I'm given by him is the best but, in the listed uses for 304 I don't see automotive exhaust listed and I am in the process of trying to find out more information.

Does any one have long term (5-8 years) experience with an aftermarket 304 exhaust system?
Any insite in the stainless exhaust and fabrication process would help educate me and generate a better product info for us.

 

If we were in court of law, I would be disqualified for heresay, but I have heard that T304 Stainless Steel exhaust systems are OK, but 304 is nothing special. When a exhaust manufacturer says their product is made from 304 Stainless Steel, its good material but not the best grade of steel. It sounds to me like its the best looking, but not the best steel for longevity. I have read many references in the aftermarket mentioning T304 grade of stainless steel. As I said, this only heresay, but it fits with what Stan is saying. My opinion only, I heard/read about this a few yrs ago.