DONAIMIAN

iTrader: (18)

After looking at most Y-pipes, ive cam to the conclusion that the way to get the best flow in the merge is to use the flowmaster merge collector. The thing about this is all long tube headers have a 3 inch colector. The flowmaster merge collect has a bigger outlet that the two inlets and them most cat backs are only 3 inches, same as the collector, meaning that your gona need a reducer somewhere along the line. Ive looked at 2 different Y-pipes, the PPC Y-pipe and the QTP Y-pipe. Both these Y-pipes use reducers somewhere along the line, the only difference being is that the PPC y-pipe uses 2 reducers right off of the header collecter(but you still have the option to run one collector at the end of the y-pipe), and the QTP uses 1 reducer at the end of the y-pipe. Point being is what would be a better position for the reducer(s) right off the header or at the end of the Y-pipe. With the reducer comming off the collecter, it seems like it defeats the purpose of having a 3 inch collector. but at the end of the y-pipe seems like it does just the same. The 3 inch flowmaster merge collector that QTP uses has 2, 3 inch inlets and 1, 4 inch outlet. So what im basicly trying to find out is what would be the etter place to put the reducer cause its gona have to mate up with a 3 inch cat back in the end. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

DONAIMIAN

iTrader: (18)

ttt
someone has to have thoughts on this

BLUEBYU

iTrader: (1)

Is there a 4" inlet and 3" outlet cutout. That would be perfect.

Colonel

"Point being is what would be a better position for the reducer(s) right off the header or at the end of the Y-pipe. With the reducer comming off the collecter, it seems like it defeats the purpose of having a 3 inch collector. but at the end of the y-pipe seems like it does just the same."

Necking down right after the header collector does in large part negate having 3" header collectors. But, going from two smaller pipes to one bigger pipe is not a bad thing so long as the one bigger pipe can flow what the two smaller ones flow.

The QTP doesn't reduce down in the Y-pipe, does it? I mean, you have a 3" Y-pipe that merges into a 4" collector. Only after the collector does the 4" go down (mine goes to 3.5" but you can have it configured however you want.) If it goes down to 3.5", that's almost enough to support the two 3" pipes (I think 3.75" would be about perfect.) Take into consideration that the charge cools the farther it gets away from the engine (therefore it shrinks and requires less flow area) and the 3.5" even more closely matches the dual 3" pipes. Now all you have to do is not neck down any further after the Y-pipe collector.

That's how my exhaust setup on my '02 is. 3" header collector, 3" Y-pipe, 4" collector, neck down to 3.5" and then a 3.5" cuttout.