[barmato]

Ok I'm thoroughly confused. In some threads people say the stock exhaust is 2" from cats to Y-pipe and in others I read 2.25". I also see 2.25" from Y-pipe to muffler in some places and 2.5" in others. Then I hear some people say they installed a new muffler with 2.25" in/out and others say they installed a 2.5" in/out. What's the deal?

My truck is an 07 CC 4.0. People don't always say what year truck they have or which engine it has so maybe that's where the confusion comes from. Either way I'm looking to replace my muffler and Y-pipe and I can't figure out what size I need.

Thanks for the help.

 

[woodb01]

Here is what I did (see the pictures)

http://www.clubfrontier.org/forums/f11/stock-exhaust-piping-measurements-48416/#post731397

See my signature line for the truck... 4.0L.

You can see in one of the pictures that the stock pipe from the cats is 2" but the Cat outlet is 2 3/8".

You can see the info on what I did and after having VERY good results in power / performance I'm going to make one more Exhaust mod. At the modified Y I did I'm going to go with 3" pipe and a 3" exhaust all the way back.

Doing some simple math I figured out that the opening of the two pipes I have and then going with a 3" pipe and exhaust will give me a little over 80% of the flow of the diameter of the 2 custom pipes I now have. other than a true dual exhaust I'm not sure I can get any closer.

Here are the things that I have noticed actually made a difference (could tell by the seat of the pants, not a dyno):

1. Synthetic oil 5W20
2. Synthetic axle oil
3. CAI
4. Remove the "Y"
5. Superchips ONLY to remove the WOT restriction (haven't noticed much difference otherwise).

I've tried a LOT of stuff and haven't noticed a lot.

I'm still going to do the following soon:

1. Do the 3" pipe and muffler (in the next 30 days)
2. Change out at LEAST 1/2 of tranny fluid with synthetic AND drop the pan and clean out any assembly debris.
3. Put an in line transmission oil filter to make sure the tranny fluid is ALWAYS clean (helps with shifting, MINIMAL help with mileage if at all, and helps tranny last while staying cooler).
4. See about running hotter plugs (only slightly hotter).

 

[2WD_NISMO]

Woodb01, you use 5W-20 oil?! How long have you run it?

 

[woodb01]

Woodb01, you use 5W-20 oil?! How long have you run it?

Just started. Bought a 5 quart jug at Wal-Mart the other day of Valvoline SynTech. It has an online registration and guarantee for 300,000 miles if you register online.

Figured if they are willing to back it up like that it certainly can't hurt to try it. Also I do know that the lower viscosity oil (lighter, slightly thinner oil) WILL improve power and mileage but I was a little concerned about wear. But if Valvoline is willing to stand behind it until 300,000 miles I don't think that is an issue any more.

Haven't really noticed a big difference yet, but will find out with next tank fill up.