just a quote from london biker :

Boosting the stock power from 46bhp up to almost 52bhp, these exhausts also produce an incredible extra 16% torque - which in laymans language means a big hike in the power band from 2600rpm - right up to 7200rpm, the biggest increase being in that much used mid-range 3800-4400 rev band, where the stock power flattens out.

Can anyone confirm if this is the case with the pipes fitted as standard and no other fueling or engine mods.

I suspect its a load of ballony but it would be interesting to know all the same.