Has anyone done this before or atleast looked to see if there is enough material past the flange to do so?
Factory hr ypipe inlets are about 2" in inside diameter. To get to 2.5" you would only have to trim a 0.25" around the inlet opening from the flange on.

Let me know your thoughts on this...

*Im doing this because an aftermarket ypipe would have 2.5" openings. That is good however it branches out to 3inches. Then the exhaust would be hitting a brick wall(rasp city) with flow from a 3inch pipe to the rest of the stock exhaust at 2.5inches.

 

The inside of the flange is the diameter that the piping will be after the flange so obviously I can't port whats not there.....next week ill have a shop cut about 2.5-3 inches past both inlet flanges and then have them incorporate 2.5" piping with the larger flange and a smooth merge from 2.5" to 2".

Im 100% confident that this will eliminate my rasp since my Art pipe install due to the Art pipes having 2.5" outlets and hr y-pipe inlets at 2".

 

I hope it works for you, but mine is still raspy as hell over like 1/3 throttle or so. My resonated test pipes are 2.5 out to my 2.5 inlet y-pipe which exits at three inches. I had a 3" pipe made and out to my magnaflow pipe. I immediately hated the rasp and have tried almost everything to remedy it. I had a vibrant resonator welded in and although it dropped the tone a bit, the rasp was still present. I even tried dremmeling out my gaskets where it was obviously restricting flow (ie black rings forming on bits of the gasket). My next try will be to pull the magnaflow muffler to see if it is the problem. They always sounded good on my v8's but maybe not with the VQ. If the muffler isn't the problem, I may just have to bite the bullet and try getting the headers I've been wanting to get. Keep us updated as I'd like to hear if your problem gets fixed. Good luck man

 

Thanks I hope it goes smoothly. If my plan fails then I hear a resonator after the y pipe is a good solution.

 

the rasp is cut in half now..its only at about 3000-3500 rpm under medium throttle..very liveable

 

I got under mine when I did my oil change today and revved it a bit. I'm pretty sure mine is coming from the flex pipe section on my Y-pipe. I'm debating on getting that bit welded up with solid pipe but am afraid it will start to rattle. I too cut my rasp in half though because I noticed my mid-pipe was a bit loose and the gasket was off a bit.