If I put Monster Ovals on an 09 Road King will I get better fuel economy and power, or better power and less fuel economy?

 

It really depends on the fuel injection tune that is done at the same time. A tune that draws fuel away from the "cruise" range will almost always net you better fuel economy, regardless of exhaust. Most canned maps are built with performance in mind, so not as good on the fuel mileage. Auto tune systems are typically the best for getting the best performance with the best fuel economy. If no fuel modification is done, then you can bet you will gain a little performance, gain engine heat, and lose mileage.

Corey

 

I just put them on my 103 build but havent tested enough for mileage yet but my power band has changed. I had crushers and had hardley any low end but all mid and top end, anything less than 2900 rpms was lugging it. Now I have tons of low end, mid and runs good at top for what I do. I can now run at 2400 and it picks right up. My experienced builder told me the powerband will change.

So in essence I can run down the highway at a lower rpm, which should give me better mpg's. I need to retune it cuz it is a little too fat at idle and take off. Definitely no more popping on decel at 2k rpms.

 

I got greater than 180 mpg on mine over a 2400-mi trip. Got 230 on one ride. I have Stage I w/ SERT, V&H TDs and MOs.