Ok, so I got myself all worked up about doing a full on exhaust, LT headers to high flow cats, new Y, to Magnaflow muffler, single 3" tubing all the way back... then while doing some research on the subject (so I dont sound like a total idiot) I find out that #1 there arent any LT headers for my 2500, and #2 I live in the Republic of Kalifornia with communist emissions regs, which most likely wouldnt let me run them anyways. Bummer.

So, my question is.. for the money, would it even be beneficial to still do high flow cats, new Y pipe and new muffler without the headers? And would it even be CA legal? I kind of have a feeling that the high flow cats wont do squat without the headers. Im sure a better Y pipe would help, but is it really worth it for the price? (I will also be ordering a RamHammer as soon as they are shipping to compliment whatever exhaust system I end up with.)

Secondly, to even get off my own subject here... Im doing the 4.56 gears soon, but I cant really find any info on the stock 2500 LSD that I have, or even locate any aftermarket LSD's for my 10.5" rear. Ive read all the horror stories on the 9.25 LSD's, wondering if it is the same for the 10.5?

Thanks,
John

 

Look into a set of edelbrock shorty headers. They are smog legal.

High flow cats are a joke. Did you know that the hemi already comes with high flow cats? It's very well kept secret.

Until you get into serious cams (and I mean BIG cams) and big valve heads, you won't see any benefit from removing the cats.

A set of shorties and a new y pipe will be a huge improvement to your exhaust flow and still keep you smog legal.

 

Take a reading with a Backpressure gauge kit (about $30)
through a front O2 sensor bung
of your present exhaust.

Anytime the backpressure exceeds 2 psi
on a 330+ hp engine (notice I am not using 345)
you can see gains of more than 5 hp
by reducing it to 2 psi or less

You are correct about CARB & Kalifornia (& and 14 me-too states now as well)
but if you are really serious and determined
buy the CARB certified Edelbrock shorties with their certificate and plate,
have a custom shop lengthen them to 38 or more inches on each primary
and replace the 4 into 1 merge connector
with two Y connectors
recoat the modified units
using a company like Swain, Airborn, etc

Rest assured that the longer tube header
will not increase your pollution output
anymore than the CARB certified shorties would have.

There is a small increase in NOx pollution with lower exhaust backpressure
when the throttle opening is in the 40 to 80% range
in case you care about such things
but since you are thinking about new catalytic converters anyway
your pollution will almost certainly go down.

Most factory original cats are only working a 50% efficiency by 50,000 miles
so new ones always help tremendously

Don't expect more than a 3 to 6% Torque increase
even with the LT headers

 

Just move. Show California you're not going to be bullied.

 

You can't modify the edelbrock shorties and pass smog. Part of the requirement is that the cats not be moved from their original location.

 

Well, it seems like you only get really minimal gains from the shorties, for the near grand i would spend getting them in there. Dont know if i can justify that to myself. thats just what ive picked up about them through reading on here, i am still no expert nor do i have real world experience. maybe ill just end up doing a y-pipe and muffler.

anyone know anything about the 10.5 LSD?

 

A grand? You should be able to get shortes for around $350. And they do make a difference.

 

I wouldn't even bother with the Y-pipe...the nature of the Y-pipe is what makes it restrictive not necessarily the pipe diameter. Shorties will show more of a gain as your mods increase...on a stock motor the gain will be minimal.

 

nice post there Hank.

 

I must be reading that wrong....