[awoods9520]

"The tune your seeking from tuners is an emissions present tune."

Actually no, he will still need a non emissions present tune. He will still have the emissions equipment installed but will be bypassing that equipment using an exhaust cutout to route the exhaust through a separate pipe. If he were to run an emissions present tune without the exhaust running through the emissions equipment then it will throw multiple codes and most likely go into limp mode.

 

[awoods9520]

Would the truck get upset about having a Y pipe being on there at all times? Would it notice the loss of pressure and throw a code? Essentially have half the exhaust go through the stock, and the other half out the other part of the Y.



(Throwing physics in this, a restriction device would need to be put in the Y to equally distribute the pressure.)

Yes it most likely will not have the correct or (known) values reading on the exhaust pressure sensors, temp sensors, etc. Plus you would actually be doing more harm than good because come time for a regen, it will be losing too much heat through the open pipe and will not be able to reach regen temps.

 

[awoods9520]

Like said before, you will most likely fail the visual inspection of the guy knows what he's looking at. If that's not an issue to you then it will work fine as long as you have a delete tune in it and have a valve in place to route the entirety of the exhaust flow through the open pipe. As for the on the fly tunes, I'm not 100% sure you can switch on the fly between delete tunes and non delete tunes, that's mainly for timing and power levels. But I could be wrong on that. Either way it only takes ten or fifteen minutes to load a new tune using my autocal usually (not including time to load tune from my computer).