None! This will soon change because of ever-tightening emissions regs
It used to be we only had to worry about how much power an exhaust added to our bikes. But now, with the Feds clamping down on noise and emissions it's getting more complicated out there.
But Yoshimura might have just the answer. The company's R77 slip-on exhaust now comes in an optional "green" version. That's not to say that Yosh covers the shiny pipes in lime-colored paint; rather it has incorporated a performance-oriented catalytic converter into the exhaust. You get all the sound and performance upgrades you're used to with a slip-on can, but also the reduced emissions given by the standard catalyst-equipped exhaust. In fact Yosh even claims improved catalyst performance, with even lower emissions than stock.
The system is based on the firm's well-regarded R77 exhaust in stainless steel construction. Stainless is needed because catalysts work at very high temperatures, which could damage carbon and titanium components. The R77 Catalytic System uses a fabricated underslung chamber that replaces the large stock setup.
The weight loss isn't drastic due to the stainless construction and catalyst fitment, but you still save a decent 3.1 pounds on the CBR1000RR (the only model it's currently available for). In terms of power gains, this is a road-legal slip-on can so you'd not expect a lot, but Yosh claims a power boost of up to 8 HP in the midrange with torque gains of 10 LB-FT.
-Three-pound weight savings
-8 HP/ 10 LB-FT gains Price: $699
Web site: www.yoshimura-rd.com
What's A Catalytic Converter?
Put simply, a catalyst is a piece of honeycombed ceramic or metal that incorporates precious metals into its surface. These metals (palladium, rhodium and platinum) have a very special effect on exhaust gasses when hot. They "convert" the poisonous carbon monoxide and unburnt hydrocarbons found in dirty exhaust fumes into non-toxic carbon dioxide and water vapor. That means reduced smog and cleaner air.
Cats On Cars
Cars have had a tougher time with emissions than bikes up until now, and many cars won't work properly (without tuning) if you remove the catalysts in their exhausts. Gas sensors in the exhaust system "sniff" the fumes and light up the Check Engine light on the dash. Some may even limit performance until you sort it out. As a result, auto tuning firms have developed special "race cats" that generally use smaller elements than stock converters that give similar emissions reductions while allowing more airflow, thus improving performance. Expect more bikes to go down the car route as regs tighten, and more cat systems like the R77 to appear on the market.