IMHO The Akra shorty is purely expensive bling.
I have one because i love the look of it. I'm sure it adds nothing to my bikes performance, but it sounds very nice (with the powervalve/zorst flap dodah disconnected).
And i think my todger has gained 2" in length
That Yoshi R55 looks bloody nice as well though
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Garage:
2010 S1000RR Motorsports - Akra Shorty

2009 R1200GSA - Alpine White and fully loaded.

2008 BMW 635d Coupe...Diesel burning missile cage

2002 Jeep Grand Cherokee CRD....High Plains Drifter