LLY Cat Exhaust Question

[Carli_max]

I want to install a 4" exhaust on my 05' LLY. I've read that others are throwing codes when removing their Cat (For Testing Purposes Only!) Has it been determined that trucks with California or NY emissions are the only ones throwing codes? I looked at my invoice sheet from the dealer and it says I have "NE1" 50-State Emissions. I'm not sure if that's the same code for California/New York emissions. Also, if I have to keep the Cat, and I get a Cat-Back System, will I still get some of the benefits associated with changing the exhaust ie lower EGT's quicker spool up...... In other words, is it worth it??
Thanks in advance.

[chikenstiker]

I had mine through codes after adding an intake as well and I already had the EDGE. It seems not everyone has had the problem but if you are going to put in a programmer and maybe intake I would leave the cat. I actually took my full system and added just the cat back in, it is still better thsn none and better than the cat back. The codes were P401 and P404 Low EGR.

[bigbud450]

Try "finger stick diesel egr" on google and you'll find a remedy for error codes and check engine light for the lly duramax. $25 and no more errors on modded lly's.

[OC_DMAX]

From what I have read, certain EGR flow related codes are possibly set in an LLY when removing the CAT no matter what emission version you have (CA/NE or Fed). The SES/Check Engine light is only lit on the CA/NE emission models, where the Fed model does not actually illuminate the light (codes are still present in ECM however).