Sounds like the biggest question is whether you want to pay the dealer to install and keep the kit warrantied, or install yourself and not covered.

I have 4,000 miles on my stage 3 with 0 issues. Not sure how much you've read, but there are bolt in aftermarket cams for the M8 that will put out the same numbers as the EPA compliant SE stage 3 kit. And as DR BUICK stated, if your going to go SE, i.m.o. the stage 4 is worth it. The numbers I have seen have been in the mid 120's tq and hp.

 

Yes exactly. If I have the dealer do it now, my bikes warranty will cover it. If I do it myself later my warranty won't void but the vehicle warranty won't cover it. The M8 seems to be reliable, trying to decide what to do. Honestly I'd rather have the 117 kit from fuel moto with the woods cam but then I'd need to use a dynojet PV to tune it and poof your powertrain warranty is gone. It won't be a problem where I would be taking my bike normally, but if I'm on the road and have a problem and I go to the wrong dealer I might get caught.

 

I have a '18 Breakout w/107. Just had Stage 3 installed using the Harley tune. First, everything works with no hesitation, flat spots or other hiccups. I have Harley Street Cannons installed and was disappointed with the sound. It didn't have any punch to it, kind of milk toast. With the compression bump to 11:1 the sound is much better, about where I want it. I won't anger the neighbors, but everyone will know it is a Harley. The new cam really makes itself known at idle. Love the new hit when each cylinder fires and the burble. As far as the power, it has more, but it is so seamless that it doesn't seem to be a dramatic improvement. It really feels like what it should have been to begin with new, not something you have to spend 5 grand for. I guess I was hoping for it to be able to make my heart beat faster, something that requires a seasoned rider and still has to be carefully controlled.
I have a ZX-14 with 200hp at the rear wheel and it does provide an adrenaline rush every time you max the throttle, feels like it is always on the edge of control. I didn't expect that kind of increase, but I was hoping for more than I received. Am I glad I did the upgrade, yes. Given what I know now I would still chose to do the Stage 3. From the hp/torque graphs it looked like Stage 4 requires high RPM for max performance. I choose Stage 3 because I don't normally run around at 4500 RPM. I wanted something that was useful the way I ride. I was hoping for the best of both worlds, good torque down low with a big kick at max throttle and RPM. Still, I am glad I did it.
If you are thinking of going Stage 3 you should know what to expect. You get a good increase that is very smooth and refined in use, just don't expect magic.
As far as cost I was quoted 16 hours for the installation($2000), parts ran $2411. The major plus is that I have a factory warranty on everything. If you go with a non-factory setup and blow the motor the extra for the labor you save will seem very insignificant compared to what you will spend to get going again. You may be down a couple HP with the factory setup, but it won't be noticeable/significant enough to justify the risk if you have problems. Plus you have to go with a tuner on a dyno since there is no standard tune. You have to hope the tuner will get it right the first time and you don't wind up with problems with hesitation, flat spots, or detonation. I can testify from experience that a inapt tuner can blow your engine by running it too lean and adding too much timing. If that happens you get a "Sorry about that, but we are not responsible."
With the factory system there is just no drama. It works from the first startup. I would prefer riding rather than running my bike around trying to get it tuned properly. Life is too short to have to put up with that kind of crap.

 

I got a new '18 RGU and had the Stage III kit installed almost immediately. I chose it over the IV because I like the cam profile better. I have only about 4500 miles on it now, but I can't complain. I would be curious to know how much more a real tune could impact the way it runs, but it runs out pretty good. I paired it with V&H crossover headers and Reinhart's with the cheap option hi-flo SE air cleaner. I would do it all again, and have kept my factory warranty.

 

Wait. I'm confused. Are you saying you did NOT keep your factory warranty? Or you wouldn't do it all again so you COULD keep your factory warranty.

And if you did void your warranty, which with those headers you did.....why not get an aftermarket tuner instead. Sorry, like I said, I'm confused.

 

I chose to look past the warranty for a few different reasons. As I see it, if I'm going to buy performance upgrades I don't want to be held back by EPA compliance. For those bike owners who live in states where they must be compliant, the SE stage kits are probably the best option. I personally feel that the quality of most aftermarket big-bore kits is better. For maximum performance aftermarket is the only way to go.

As far as "grunt vs top-end HP" goes, the cam and the exhaust system are the primary considerations. While my cam is aimed for higher-RPM power, it certainly isn't a slouch on the low end. I have the wrong exhaust system for torque; it begs for a good 2-into-1 setup. I may revisit that some day, but for now I love the sound and power of my setup.

It really comes down to your end goals and if you're willing to give up the factory powertrain warranty.

 

Do you have your Dyno sheet? I'm curious what your curves look like. We have similar builds. I'm running a 2-2 exhaust
system.

 

Sure. I have since ironed out the dip and seat-of the-pants HP went up also since this dyno run. I have a completely different intake on the bike; my original wasn't flowing enough. I need to get a new dyno run. Here's the original.

https://www.hdforums.com/forum/milwa...l#post17700181

 

I love the stage III in my RKS. 5k trouble free miles since the upgrade and tons of power whenever I need it. I didn't go for the stage 4 as I didn't think the 10 hp was worth the extra $1k for parts. The sound with the MK 45s is great as well.