I have a 2009 zx14, muzzy full exhaust, took the upper part of the exhaust off to put another exhaust on. The muzzy headers are still on. Took the bike into shop they could not fix problem. From 0-4000 rpms giving the bike full throttle the bike sputters real bad like it is trying to get fuel. At 4500 rpms the bike is normal with throttle response. I do have a power commander. Mapped for muzzy exhaust. Any ideas what the problem is?

Sounds like you are running a full exhaust made from two dif systems. If it was running good with the Muzzy muffler and headers and now it runs poorly with half Muzzy, half whatever else you put on, I'd bet it is the whatever else that is causing the problem. You probably need a tune for what you are running. have never heard of anyone running different exhaust parts together. If they fit, I don't see why it can't work but you obviously aren't going to get good performance without a map that fits the new flow situation you created.

Hey I appreciate the response, I just bought a Brock's slip-on so I guess we will see where we go from there.

I have a hunch there is a Brock's header in your future...or OEM header. Contact Brock from his site. I bet he will be up front with you about whether or not his muffler should work with a Muzzy header.

It sounds like you are saying:

0 to 4,500 rpm runs like it's starving.
4,500 to redline it's normal.

If that is what you are saying = Uninstall the pc from the hot side. Injectors still make a ground or resistance you keep pulling the pc ground off and the same problem still exists. Pull hot off, not the ground on the pc... Make sense?

I am a computer bike. I am low/mid-mid/high kind of map. I sputter all up to mid/mid changes to running BETTER. Well, it sure sounds like a map scheduling in the low/mid range. 0 to 4,500 is almost there. Or say where the pc map is layering over some bad cell numbers?

It can't be bad plugs, if it cleans up from mid to high. It can't be the fuel pump, if the pressure is at the top rpm range? So, spark/fuel have been addressed. Compression is a given, being it starts for now. Can't be a bad ground if it cleans up at the top, remains consistent at 0-4,500rpm range all misfiring whatever. Can't be a rat's nest you switching pipes, being it cleans up at the upper end.

And no damage to bike you beat crap out of it without piggy. Especially slips.

@hub and @rook after my Brock's slip on is installed I will take it from there, hopefully this solves the problem but Ill guess I have to wait and see, if it does not work I will start troubleshooting. I appreciate that you took some time and helped me out.