Well, my boat has been feeling very sluggish and didn't want to accelerate. I kept going back to what I did on the car, and finally came across the noob mistake I made. When going to short ram air intake, I thought that the throttle body "screen" was just a filter to catch large particulate and removed it *facepalm* I know that some of you are going to argue it doesn't matter, and on your build, maybe it doesn't, however, there was a HUGE improvement in throttle response and my mpg went up as well as stabilized my idle some.
On a second note, I have been dealing with a P0420 since upgrading my catalytic converter to high flow. I tried using a bored out spark plug non-fouler which worked but after less than 1000 miles, I got a code for my o2 sensor heater short. Upon removing the o2 sensor, I found more rust and condensation than I could fathom! I removed my o2 sensor and just dealt with my code.
As you might already know, I just removed my resonator and upgraded my mufflers to dual borlas. Strangely enough, my code disappeared!! I thought maybe I forgot and cleared the code and that it would come back shortly. It's probably too soon to say for sure, but I'm already over 500 miles without a return of the dreaded P0420!
Wondering if anyone has experienced anything like this before. My hypothesis is that the reason it was throwing the code in the first place is that the exhaust was backed up (plugged muffler?) etc. and that by removing the restriction, it could flow correctly. Strangely my mpg has improved up to around 22mpg mostly stop and go city driving and around 30mpg highway! Not sure if the exhaust has something to do with it.