mrpositraction

That is what I did on my 07, cut the Y out and ran it true duals.

02reaper

iTrader: (2)

Looks good.....Mandrel bends too?

mrpositraction

Dang skippy

Bought one of those kits on line and had a local shop cut them to fit. Had them install the muffler at the same time. Then I put mandrel bends after and out eh side:





It sounded good until I supercharged it, then you could hear it was choked.

mechanicboy

Agreed. That is why when I did my exhaust I cut the y-pipe out because it necks down to 2 1/2". The ecoboost does the same thing at its Y-pipe. If you cut out the Y-pipe and changed the entire system to a larger size then you might see gains. add the downpipes and you should have a noticeable gain.

Centexguy

Lots of shoulds but no confirmeds.

Joewee3.5

So you want proof that a different muffler will flow better than stock or a 4" will flow better than a 3"? Even though the stock muffler is straight through I don't think that necessarily means it flows better than other straight through mufflers. Seems like gases could roll around inside a bigger muffler and cause some turbulence. Who knows, I'm just thinking out loud.

Centexguy

4" is overkill. I want proof that an aftermarket 3" cat back with a straight through muffler and off road down pipes actually gains performance over the factory cat back with off road down pipes. Dyno numbers and track times. Not manufacturer claims. From actual individuals. I'll even take it with stock downpipes. Certainly someone on this board has done what I'm asking.

Joewee3.5

4" Overkill for performance, maybe yes. But for sound you'll never get a better sound from 3" Than you would with a 4". If you want silent then you're right. 3" is the only way to go.

Centexguy

Depends on what sound you are going for.

engineermike

Centex, I don't have links, but a while back somebody swapped the stocker for a Blowmaster and posted dyno charts with a 15 hp gain. I am highly skeptical, though, for many reasons. Not the least of which was when someone made several runs through the stock cat-back, then dropped it and made several more runs. The gain was zero at the track. If no exhaust is no faster than stock, then there is no reason an aftermarket exhaust would be faster than either one.

Technically, larger pipe will have less backpressure. However, if stock is negligible, then larger pipe or no pipe will not show a measurable difference.

And before anyone says you need backpressure or velocity to make power, you're simply wrong so don't bother.