Would coring the stock y pipe give the same results as aftermarket ones? What's the main restrictions in the y pipe?

 

removing the precats on the stock y is where the
performance gains come from...

the aftermarket y's are 2.5 vs the stock 2.25

 

It would help, but I think a big issue with the stock y-pipe is the fact that rear down pipe directs the exhaust gases forward. Not only do you have back pressure from the exhaust from the back cylinders colliding with the exhaust gases from the front cylinders, you lose the scavanging effect.

 

I think this is where your gains come from, not the pre cat issue. The pre cats flow pretty good, just as our stock cat flows good. The key to getting the exhaust out quicker is getting rid of the colliding gasses and make the pipe scavange or actually suck the gasses out.

 

After looking at my stock Y-pipe I think I could make a better flowing pipe out of paper clips and tin foil. In addition to the rear pipe flowing into the lower section the wrong way, it has many tight bends (necessary to accomade the pre-cats I guess) and right after the flange that conects to the front (or maybe it's the rear) header the pipe is crushed to almost 1/2 its diameter, I guess it has something to do with the oxegen sensor there.

For $225 my Warpseed Y-pipe makes no unpleasant noises and fit like a glove. Removing, coring and reinstalling the stock Y-pipe would be fairly expensive, wouldn't it?

 

Well so much for that idea. Thanks for the help.