would it sound louder if i just put the high flow on and left it y-piped? cause i dont want to lose any power by opening it up 2 much.

 

also the 2008s have 2 cats, unlike the older models with 4. if that makes a difference.

 

You will still have a good sound increase.


The two cat systems are a couple DBs louder.

 

ok thanks

 

also, will i get a CEL if i put in high flows?

 

I haven't actually seen it done on the 2-cat systems, but you shouldn't so long as you don't move the O2's. When I gutted my precats and installed high flows on my 04, I didn't get a code.

 

As long as the rear '02 is mounted after the new hi-flow cats you will be alright. Dont buy cats with O2 mounts in them, they will give incorrrect readings and throw the CEL.

 

ok. i am getting the magnaflow high flows that u gave me the part number to earlier. i dnt think they have the mounts in them.

 

Unless you go with something like 3" true duals you wont notice any power difference by doing it. Mine is 2.5" and I think my torque actually increased, I would run true duals (make sure to use either an X or an H-pipe) and see if that is loud enough for you before I started messing with the cats. If its not then you can always do the cats later, my truck is extremely loud in the cab and outside and my cats are the stock 2. You can check out my sig for an idea on how it will sound.
BTW It will depend on your dealer, but changing the cats could very well void your warranty, so I would check with them before I did that with a brand new truck.

 

They dont, so you will be alright.

 

ok sweet thanks. and yea i probly should check on the warenty info

 

# 94106. i looked up that number an the magnaflow website and it said it was for chevys and older f150s. but that will still work on my 08 and be emissions legal?

 

Yes. Its 2.5" and does not have an O2 bung, with the sensors mounted in the pipes after the cat, it will work fine.

 

ok. ill get them in next week. thanks alot everyone