I was searching on the forum and read that the M2 and Pettit DP do not require removal of the studs, what is different about these two that allows the studs to remain in place? I have a Bonez dp on my car, which was installed by the prevous owner, and he told me that I must remove the studs. Also I though the Bonez was suppose to be SS, but I notice rust starting on the piping. So I have been thinking of replacing it for the those two reasons, plus getting it coated.

I would appreciate any info possible, and pics would be nice too. If you are selling either hit me up as well.

 

1) Stainless will show a little rust when used at extremely high temperatures. I think they call it scaling, actually

2) M2 dps are smooshed at little at the first bend in the pipe so there is more space between the pipe and frame. That way, if the nuts come off and the studs stay in, you can slip the pipe over. I have the Pettit pipe, and it does not appear to have this shape, so the studs must come out. IME, the studs come out anyway and the nuts stay attached to them, so it's not a big deal.

 

I got the bonez on with the studs on...

 

I have installed my Bonez downpipe twice now without removing the studs first. Not a problem.

 

Is that with the stock long studs, or the replacement shorter ones?

Dave

 

Ok, all of you who put on Bonez downpipes, how did you get the bottom rear nut onto the stud? on mine, using the replacement shorter stud, there is not enough room between the pipe's bend and the end of the stud to get the nut over. Maybe mine had a manufacturing flaw? Or do I need to buy a smaller nut, dent the pipe, etc? Anyone have this problem?

 

Put that nut on first. With the pipe loose you can pull it away from the turbos and therefore give yourself room between the end of the stud and the downpipe to start the nut on. Run it down snug and then install the other three nuts. Now tighten all four.

Stock I suppose because the last time I installed the downpipe was when I replaced the turbos and at that time I replaced every stud and nut on them. Used all stock Mazda parts.

 

Well it looks like rust to me, I plan on getting "A" coated and I am not sure if it would be best to get my cuurent one or buy a new one......

Where can I get the replacement shorter studs?

 

Ray at Malloy sells the ones that are slightly shorter. IIRC the factory put a mix of long and short studs in, and Ray just sells the shorter of the two for replacements. You really don't need the extra length.

Where is the rust? It's possible that the welding made certain parts of the pipe more susceptible to rusting. It's also possible that winter salt (chlorine) environment was too much even for stainless steel. But I'm no exhaust system guru - I'm just pitching out possiblities.

 

I bought the SS Pettit DP this past summer (when I got the FD). They sent all new studs. They were all about a 1/4 inch shorter than the stock studs. i think the reason is because the precat is sort of flattened out where it meets the manifold. It allows for more working room and longer studs. I say working room - but if you've done the job - this is the most cramped you might ever be.
The Pettit DP has a mandrel bend that doesn't provide as much working area when it meets the plate on the end. I tried to get it on the stock studs and they would hit the pipe. Stock studs were too long.

 

I appreciate the pitches.

Well from what I was told when I bought the car they do not salt the roads in Delaware and he never had it out in the winter. The rust is really the whole lenght of the pipe, not just spots. My only thought is that it is not a "Ture stainless" I have seen other stainless pieces and they just look brownish/tan in color but have the same texture, this has a slightly rougher texture to it.

I have another question since you brought up the welding, does anyone know if the M2, Bonez, and Peittit use SS flanges? Cause I know some of them use steel.

 

Don't know. Mine came covered in hi-temp coating.

 

They do not use salt in Delaware, they definitely use sand. (Ohh, and sand is AWFUL in winter, it gets into everything and doesn't help with the ice at all)

It sounds like something is up with this pipe - but if you sand off the flanges then it will be just fine. Coated, wrapped, or bare - I don't think that aspect matters much.