Hey guys,

I have an 08 chevy avalanche with the 6.0L. I just lifted it 4" and now I'm looking to get some of that power back that the 33's robbed me of. I already have the stock 4.10's, a cai, and a mild nelson tune. I'm thinking of getting headers and exhaust done next. I've never had headers and I've only had flowmaster 40's on past trucks. Which headers would you guys recommend? I've been told about the pacesetters (don't know the exact ones) by a handful of people and thorley and jba by two other people. I want long tubes. Also, which exhaust would you recommend and how should I run all this? One muffler Im guessing, right? What size tubing? I want turn downs or twin tips out one side I think if that even matters. Any other advice? Thanks in advance.
-Ben

 

You need to build some low rpm torque to overcome those big 33" in that case definitely go to Thorley TRI Y's not for high rpm race truck but great for low rpm torque towing and street performance

 

tsp on the right.. theyll hook u up. ->

 

thanks guys, im trying to find the part numbers. when i go to the thorley website they give me thy-309-c for ceramic or thy-309 for chrome. i want ceramic but are they longtubes (i thought this is what made the most torque and power, correct)? cuz the pic for the chrome ones is shorties. also, it says no smog fittings. im assuming it still has o2 sensors, correct?

also, what do i do after the headers? there is so many options im not sure what i need. i just want a y-pipe that deletes the cats. what muffler? 2.5" or 3" tubing?

just fyi, i think i want to add a mild cam down the road.

 

Call Thorley.they dont list a PN for your new truck because they dont have a certified set for emission .but they will know what earlier year pn will fit ....the Tri Y is a long tube the torque also comes from small diameter tubing and small diameter collector . my truck takes the 311Y

FWIWthe cats onthe newer trucks are very good I doubt you would see any gain below 6K by removing ........I and others with these trucks who want performance but no drone or excessive noise run Magnaflow and if you going to add headers get the long 22" case 3" version will fit into your stock 2 3/4"exhaust piping ......nice sound but not obnoxuoius

 

thanks, cdn. that helped alot.

 

Goose
What is your opinion of the mild Nelson tune? did you feel anything gain?

 

when you get bigger tires one of the best ways to get your power back is re-gearing. Since you already have 4.10's, 4.56's would be the next step up.

 

gonzo- honestly, i didn't feel much, but all i have is a cai for now and i had him keep it 87 octane (i get all the 87gas i want for free from my job). if i had gone to 89 i believe i would have felt more. i did notice some gain in mpg about 1.5 which i thought was pretty good for these big 33's. i think it is a good idea to get a tune though since you'll get free upgrades with the mods you do later on. after headers and exhaust im going to have him retune it.

xsport- my 4.10s should be the "recommended" or ideal gears for my tires, right? and just going to 4.56s won't help that much anyways right? and especially for that $$$ was my thinking.

 

I think stock tires are 31.6" and with the new 33" tires your effective ratio is 3.93 from 4.10. But yeah, generally 4.10's are recommended for 33's and 4.56 for 35's or bigger and i agree that the $$ spent for a gear swap isn't worth it in your case. I ran 4.56's with 33's tires and the difference was night and day, gobs of power off the line, but i had 3.42's stock which sucked ***.

If you want to run a Y-pipe i would go with a 3". But doesn't the 6.0L run a dual setup all the way back to the muffler? why not keep it a dual set up with a dual in/out muffler with built in x-pipe? just food for thought. And as far as mufflers go, i love the sound of my Magnaflows