Had an offer to purchase Vance and Hines Monster Oval Slip ons for a hundred bucks. It may be for a pre 2017 Road Glide, would there be any fitment problems on a 2017 M8? Can I get away with out a new tune or A/C? Thanks guys!

 

2016 and before slip on's will not fit a 2017.

 

Won't fit sn M8. The M8s have different diameter pipes.

Most people recommend a tune with open flow slip ons. I think the rationale is that in the stock configuration, the exhaust restricts flow more than the AC. Open the exhaust, you get more flow, and need more fuel. Then when you add a more open AC you again get more through flow, and need to tune.

 

As others said pre M8 slip ons wont fit and NO you don't need a tune for just slip ons

 

That has been debated extensively, and conclusion is that you don't "need" a tune with just slip ons, but it is recommended.

I am about to do mine. Because, since I swapped my '17 Road King for SE Street Cannons, i get a bit of pinging when I really get on it, and the torque seems to drop off about 3,800 RPMs. Both signs of running too lean. But, I could live with it. I'll be curious, and will post the results after I do the tune.

 

These motors are tune to EPA specs. They already run as lean as you would ever want them to with stock mufflers. Do you NEED a tuner for mufflers, no, but it will be even more lean and will not be running as well as it could if you add one.