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I was reading up on these and seem like they might be the way to go. However, do they bolt up to the stock Y pipe? I see they don't come with a Y pipe so they either must bolt up to the stock Y or will i have to get a shop to fab up a Y pipe for me?

and the ones i can find are only for 99-02? where can i find them for an 06?
 

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I was reading up on these and seem like they might be the way to go. However, do they bolt up to the stock Y pipe? I see they don't come with a Y pipe so they either must bolt up to the stock Y or will i have to get a shop to fab up a Y pipe for me?

and the ones i can find are only for 99-02? where can i find them for an 06?
If you want long tubes get the 99-02 ones, they'll fit your truck just fine. If you buy the ones for an '02 or later you'll get shorty headers.

310Y is the part # for non coated LT's, 310Y-C are the coated ones. Pick your poison...
 

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HOT AIR BALLOON OWNER
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For they Y they weld JUST in front of the cats, this is to keep CARB legality.

Don't want them? Just get an ORY made with some longer collectors and have even better TQ.
 

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you can get them to work on an 06 maybe even 07 classic as long as you can get someone to sell/donate to you an 05 and older y pipe, or you can do like azcatfan did and remove the cats until you can have a custom y made up.
http://www.gmfullsize.com/forum/showthread.php?t=122700&highlight=y+pipe

the carb number is right on the tag thats welded to the header and it doesnt specify year on them either (even though it does on the website) i would think with an un-modified y from an 05 and older and the thorleys could pass the visual test from even the pickiest smog nazi.

here is another link with some great pics and installed using the stock y on 0chevy4's truck (post39)
http://www.gmfullsize.com/forum/showthread.php?t=88033&highlight=doug+thorley+tri-y&page=2
 

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I'm looking at getting a set of these for my truck, are they worth the money?
 

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Officially Tucking Tire
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according to the pdf file here they are only legal from 99-01
http://static.summitracing.com/global/images/instructions/dte-310y.pdf

and i called thorley on this and they couldn't say anything other than they are legal on 99-01 only, and its because the carb number was applied for when they were made im guessing in 01, and the number hasnt been updated or revised for any newer models.

i see no reason why they wouldn't pass smog, they are the same 5.3 engine and the cats are in the same place(except 06) so whats the deal, but the smog guys are picky here and most of them have no idea what they are looking at. they just read the numbers and if they don't match your f-ed, and heaven forbid they should make a rational judgment about a bolt on item. i don't see why if the sniffer says it is burning clean, below the limits, then why hassle about the visual...
 

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Speed Holes
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The 310Y's (yes they are listed as for 99-01, but fit others) come with flanges that are meant to be welded to a cut off OE Y-pipe in front of the factory cats in order to remain smog legal.
I have them on my '02 with the factory Y-pipe but with stainless pipe welded in where the cats used to be, giving me an ORY.

Hey heavychevy, I haven't forgotten, I'm still trying to email you those photos I took of my setup but you've got to be patient, those photos are actually on my wifes laptop, which I'm not on at the moment...
 

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HOT AIR BALLOON OWNER
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My 310s were on an '04 truck and I have it's Y pipe AND headers on my '01. FWIW.
 

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Officially Tucking Tire
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bump!
anyone have any luck with passing smog with an 02+?
 
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