thinking about dumping the stock exhaust in favor of a better system. my question is it better to use a 2 1/2" to 3" y-pipe or stay 2 1/2" in and out. doing a SI/SO system. using a magnaflow muffler. which y-pipe will give the most gains on the low end.

 

Hi.

For SISO - 2.5" IN/ 3" OUT 'Y' pipe + 3" intermediate pipe, + 3" In/Out muffler

MGD

 

Yup, what he said.. i swapped out mine using a Magnaflow part... sounds a little deeper and seem to have picked up a bit of low-end torque...

 

Can't say much for power gains cause I put LT's on at the same time but I went with the maggie Y 2.5" on both ends w/ 2.5" midpipe and works great. Exhuast sounds much better and although I have headers I think the Y has alot to do with the deeper sound.

 

Staying with a 2.5" mid pipe with a straight threw muffler will boast your low end torque curve. I recommend getting a Magnaflow Y pipe and leaving it all 2.5" for MAX low end.

 

Hi.

[OT]

I just noticed something here - yer O2's may be right on the bordeline w.r.t. mounting - hard to determine the exact angle, but Innovate Motorsports (they make widebands) advises the following:

"Install the oxygen sensor’s bung upstream from the catalytic converter
(a bung and plug is included in the LM-1 kit). Any decent muffler or
exhaust shop can do this for you. The wide-band oxygen sensor is then
installed into the bung to take a reading. (Insert the plug into the bung
when not in use). The bung must be installed in the exhaust pipe at
the side or on top, NOT on the bottom of the exhaust pipe. Best
position is between 10:00 and 2:00 position."

" Do NOT install the Bung below the 3 o'clock or 9 o'clock position.
Condensation can form in the exhaust pipe and permanently damage the sensor. 6 o’clock is the absolute worst position to mount the sensor. "

[/OT]


Just fyi ...

MGD

 

Hmmm interesting bit of info thx for the heads up. I think that the stock position of the downstreams was just about the same angle...maybe like x:13 and x:47 max. If they start failing ill definitely look into that. Been two weeks of daily mixed driving and no CEL so ill keep my fingers crossed, thx.

 

With a 4" tip, now it's perfect - She'll drag house of it's foundation

http://www.troyerperformance.com/cgi...atalogno=15609

 

Exact set up I'm doing..Parts waiting on the rear floor..Gotta make it to a zaust shop...

 

I agree with AVFrog. 2.5 inch all the way to have the most bottom end. Need to keep the velocity of the exhaust higher at low rpm to improve torque numbers.
Is that what the factory is? Or is it 2.75?

 

If your running LT's, HF Cats or Catless, then yes.

A cat back only justifies 3" . That's what worked out best on the Dyno. You will gaine low and high.

 

2.5" stock on an 05.