O2 eliminator + Fuel Regulator = bad running?

I recently purchased a 2004 Interceptor from a private seller who added a couple engine mods to the machine. He installed Dynojet's Oxygen Sensor Eliminators and Turbo City's Fuel Pressure Regulators to richen the fuel mixture because he said that the VFRs run too lean from the factory. After putting several hundred miles and a few tanks of fuel (from different sources) I wondering if those mods are causing the bike to run rough.

Basically, it runs great until it gets warmed up and then it sounds like it's sputtering a bit especially when at cruising speed around town. I have it in 4th gear going about 30 to 35 mph and the tach is around 3500 rpm. The bike will sputter a bit and sometimes hesitate.

Am I doing something wrong? Could I have gotten bad fuel? Is there an issue with the mods or the combination of them? I haven't been able to find too much about the fuel regulation mods on this forum but from the one post I did find it isn't needed on the 6th Gen VFRs. Is this true?

Thanks for the help!

 

4th gear at 30-35 and 3500 rpms would probably cause the hesitatoin / roughness. The VFR's tend to ride rough under 4500-5000K. I bought my first bike - 06 VFR - couple months back have experienced that also. Was told that it was normal. VFR's like higher rpms. I typically ride between 4500 and 6000 rpm for cruising around.

 

I have both mods - no problems whatsoever. Smooth pull from any throttle position.

 

Thanks for the replies. Once I get some fuel out of the tank I"m going to try removing the mods to see it makes a difference. I'll also try running at higher RPMs and see it makes a difference.