They do jack $hit on a Banshee too, other than crack the boots and cause leaks. That was something developed before reed valves were perfected. Find one credible source/dyno chart that proves any increase. Do that and I will make an OFFICIAL APOLOGY THREAD in off topic.
BTW Banshees run just fine even without the stock crossover tube. Big carb manifolds/boots don't even have nipples for the tube. They don't even have the tube on an RZ350, which is same basic engine.