While I will consider the dual exhaust Intruder a failure, there are a few modifications that we think are helpful - not to say that they are universally accepted, but here is our list - in no particular order of preference:
1. Carbide Wear Rods. They don't steer for beans on ice without carbide.
2. Studs in the Track. While some will say not to stud a 30 year old track, we don't see it being much different than running a 30 year old studded track. 48 - 0.875" studs make a huge difference.
3. Install a lift and tunnel protector kit on the suspension. Combined these keep the studs from tearing out the underside of the tunnel.
4. Widen the ski stance. Not sure if ski spreaders are still available, but those extra few inches give a better feeling of stability. Again it can be argued that this puts additional stress on the steering spindles. We have however found no ill effect from this modification.
5. Image Enterprises gas tank neck repair kit - not needed on all sleds, but if needed it is a quick and easy solution to gas spilling out of the filler neck.
6. BR9-EYA Plugs - run more reliably for us than the BR9-ES
7. Add an electric starter. It does not need a full electric start kit, but for those times that she just does not want to fire it is so much easier to hook up a battery pack to the starter and crank it over. This is particularly true for the Intruders that seem for some reason to be much stiffer than the Invaders.