stealman1

I am wondering what the difference between the So and Ho is? I have a california model SO. What makes the ca. model 235 verse the other SO with 250?

2003Ram

The only difference between the 235hp and the 250hp versions is programming, probably timing. The 235 cali truck has a cat while the 250 is cat free like the 305hp HO. Otherwise, both the 235 and 250 versions are rated @ 460 TQ.

PS - get a Smarty and the playing field is equal.

stealman1

Can anyone verify that the 235HP. has a cat? I also have a 04.5 HO and the piece after the down pipe on these trucks looks similar, but the Cal. SO. has a longer taper. I dont know what a resonator looks like or where it goes in the exhaust system. I would like to know about the cat. or no cat. because that will effect what I do with my exhaust in the future.

Dodgezilla

The 04.5 has a CAT also..

2003Ram

The '03 and the '04 235hp SO absolutely has a cat. It looks like a football ~2-3ft in front of the muffler. It is the one Item that made the Cummins emissions legal for five states including California for those years.

PS - I have one

tuzlo

whoa whoa whoa. So youre saying the only diff between SO and HO of the asme year (mines an 03) is programming????? Can the truck be reprogrammed to be an HO if this is so?

2003Ram

There are some that say the head is different - not true
There are some that say the pistons are different - not true
There are some that say the injectors are different - not true

The only difference between the HO and the SO is the HO has oil nozzles under the pistons to help with cooling. I don't think anyone would reprogram the ECM to an HO. Your best bet is a programmer. If you load Smarty on any same year truck, you have the same output whether it's an SO or an HO.

Marco explains on his website at madselectronics.com.
(SO = gets 200+ hp on level 9)

stealman1

So my ca. model truck has a cat, I guess. That changes my muffler shopping allot. I have read allot about the muffler delete with a cat. Is that the way to go. I dont want noise, I want performance, But I will take some noise to get it. Just not allot and no drone. What should I do?

TrkEnvy

i didnt notice a lot of seat of the pants when i went straight pipe and kept my cat.. i did notice more noise but its not unbairable.. I like it a lot. I did notice the turbo spools a little quicker and I can really hear both sides of the turbo now..

FarmerJim

SO also has smaller universal joints in the rear drive shaft than the HO. You can verify this thru dealer parts dept.

nogood

if you go cat back you will notice and power gain, if you go with a turbo back there is a small increase in power and torq. you wouldn't notice 6 hp and 10 ft lbs. est. high side. that test was done on a d-max should be similar for the 5.9. the cat back exhaust is a little louder then stock but not much. with the cat in place it helps quite it down.