The best removable one (fuel/timing) that I've found for a streetbike was a Maximus, very expensive, but I don't think they make them for quads.
These units can be tuned over the internet where you take out the bike and do certain requested moves, and then download the info to guys that can tweak the tuning.
A few times of this and you are very close to an actual dyno tune, and they can handle cams superchargers, turbos, or NOS.
The next best (fuel/timing) is a piggyback unit called a Power Commander V (PCV) mid priced.
It also is fully tunable using a dyno other than not being able to effect ignition timing below 2500 rpm and not being removable, and they can handle cams superchargers, turbos, or NOS.
I have one of those and it has been excellent from the get go, but the shop I bought it from loaded the tune that came from a really good dyno tune session.
I still plan on doing a dyno tune for that last 5% or so...just have to find a guy good enough that isn't too far from home. When I had my street bike tuned I rode 2K miles to a guy in Iowa.
He is the king from the Midwest to the west for the brand of street bike I have.
The next kind are the ones most guys run for basic setups.
They come with canned tunes in them, and you select the buttons on the unit to tune it close enough for most.
These are piggy back units also and must remain on the bike.
The reason the factory doesn't tune the bikes properly is because of EPA requirements for new bikes to be sold.
The EPA doesn't care if your bike engine is being cooked by very lean conditions, but you can fix the situation by adding more fuel and sometimes ignition timing within certain rpm ranges with an advanced fuel/timing tuner. Ignition timing is the tricky stuff and is safest done by a Dyno Guru IMO.