Roughly how much power do the large kit car exhaust silencers lose compared with a higher quality race style can (eg yoshimura,racefit) which are also much lighter on BEC's? is it a noticeable difference?

They shouldn't loose any power If it is well made and made to suit the engine. Some of the normal bike cans can even be power saping. What you really need to do is get a can made for your car ie one that will pass all the noise regs for tracks days etc. Its worth spending the extra and getting a good one. Then get your self a "race can" for weekend road thrashing. Best of both worlds mate.

Hope this helps.

Matt

thats exactly what i intend to do. thanks matt

There's a noticeable difference between the two types of silencers. Like Matt says, you could have two silencers - one for road and drag and another for trackdays. If you've got a power commander fitted too, you can quickly upload custom maps for each application.

Phil