thorley headers 03 5.3 sierra california question
 

I have been searching for the last hour or so but i just wanted to make sure...

does part # THY-310Y-1-C tri y have the carb eo stamped on it? how about the 310y da c? allt he same excpet for coating right? i just need to make sure i have a stamp on the one i'm ordering.

my truck is an 03 will i have any fitment issues with it? i see it is only cali legal for 99-01 and the only difference i can find is that the 99-01 headers have an egr bung i would otherwise need to block off since i have an 03. the 03 doesn't have an egr?

so these headers should fit just fine right? i just have to cut my stock y with the supplied flanges and i am good to go? 03s have the cats down low, not like the 06 y pipe.

sorry i'm a truck engine newb

I need to look under my truck again, I can't remember where exactly the cats are, but on my 01 I'm pretty sure they're closer to the manifold. As you probally know, moving the cats from the stock location automatically fails it at inspection. What part of California are you in?

san diego. i don't want to move the cats at all. my search found it is the 06 cat that is closer to the header and the other y pipes are further away so we could just cut and weld the flange. i haven't looked under the car since i found that info just to make sure. just doing reasearch on headers while i'm at work, killing time. :)

https://www.performancetrucks.net/fo...-440406/page2/

this thread shows the y pipes and bung on the 310y header

i think i know what needs to be done now. i just need the carb eo stamped on the header and hope the smog guy doesn't research the eo, which he won't. modify the y pipe without moving the cats, which i should be able to do having an 03 y pipe. and block off the egr bung which is not utilized on my 03 5.3. i want headers now. :)

I just thought I should comment since I was the one in the linked thread posted above...

I did the same thing and had the same thoughts on it as you do, don't do it, I just had to remove my bassani headers and go back to stock to smog my truck. I thought that I could get it through smog by using an 05 y pipe and making it work and since it had the carb number it would be fine, but everywhere I went they pulled up the carb number and the carb number says 99-03 and they failed me. The smog techs WILL pull up the carb number and verify it.

This makes me wanna get those headers now since I've got a truck that'll be covered by it

I've been wanting a set of these for mine for a while now, being the only CARB approved mid length headers for my truck with dual A.I.R injection on it. but it just kills me that they are over $600 when a pair of pacesetters are about half the price and should perform better.Got me thinking about building all new exhaust with no cats and some pacesetters and just swapping my stock manifolds and cats every 2 years to smog it, I hate california

Agreed X2

yeah i just now decided to go LTs, catless with a tune. fuck it. i can either take everything off every two years or take it to a friendly place.