im thinking about buying the hedman 68470 headers and 17478 y-pipe for my 350. the thing is i need a 3 inch outlet on the y-pipe. ive read about people modifying the y to have a 3 inch outlet, which brings me to my question what exactly is needed for the mod? where do i cut and what do i weld back on? thanks in advance

 

About to modify mine that way, I'll let you know...

 

any chance you can take before/during/after pics?

 

Yes, I picked up a 3" pipe ( off of a truck) from Midas and had them, swage one end to fit over the collector, the other end was already swaged to slip over 3". I will get the Midas part #. It cost me $57.00, ouch!
The plan is to cut off the ball flange on the after cat pipe, cut off the small pipe (test tube) that is on the collector and slip it on and weld them up? I'll get pix and send 'em to you. plan on doing it this week. PM me your email address...

 

you got any pics? this isn't exactly what I had in mind, but it's interesting. I was thinking of cutting off the y pipe part and using the rest of it for true duals. easier than trying to make the flanges fit right with the bends right on them, just not sure if it would be cost effective.

 

Don't they have adapter pipes at autozone, advance, etc? I think they carry some that will fit a 3" pipe. check it out.

 

Any pictures ?

 

The entire Y-pipe needs replaced. Considering it's a 350, and considering the header primary tubes are 1.625", the 2" pipe under the oil pan is far too small. Dual 2" into a single 2.5" is enough for a stock 245 HP L98, but those headers need 2.5" to a proper 3" junction, not just adapting a 2.5" pipe to a 3" cat.
Truly sucks that a big-name company can't offer a tolerable y-pipe. Really, you can forgive Flowtech for dumping the side's 2.5" into the left side's 2.5" because that's cheap Chinese junk. And their headers are only 1.5" primaries. Again, adequate for 245 HP, but way wrong.