I am trying to make a 3" y-pipe to single 4".

I may have to modify the frame rail next to the exhaust.

Would it be possible to cut out the frame piece, and then weld in a piece of 2"x2" square tubing? Or could I just cut the piece out and weld a piece to box it in.

This where I have to cut it, see where the black marker is?
https://www.thirdgen.org/forums/atta...1&d=1362543650

 

Do you want it to have the curve like in the photo

 

Now that I think about it, I guess I could square it off, and then box it in.

Would I compromise the strength of the frame?
I have SFC, btw.

 

You could do it both ways if it were me and I have done this many times this is what I do every day I would get a 1 foot of thin wall mild steel and have it bent in a pipe bender to that shape then cut it in half then start to trim it until it is close then weld it in and grind it to fit the rest of the frame it will look a lot better then boxing it in just make sure you have close to the same gage metal as what to frame rail is so it will weld together even

 

Not if you have good welds and the same or even heavier gage metal

 

Do you have any pics of your modified frame?

 

I'm using a I pad and I can't load photos ??? I should have my desktop fixed by the end of the week then I can send you some picures but I found one here this would be done the same way you would do yours http://www.google.com/search?q=modif...RNHcdz_JglM%3A

 

What I did.

 

Can you post any pics?

 

Here's what I did.