How much power loss with stock catback?

[M@lew]

My car at the moment has a Buddy Club Spec 3 exhaust and has a K100 tuned to it but I am taking it off and replacing it with the stock exhaust this Sunday and was wondering roughly how much power I would lose with the stock exhaust on and roughly how much if I were to get a Fujitsubo Power Getter (Assuming the difference is significant)? This is without a re-tune of course.

[JonCTR]

Not sure exactly with those exhausts. I saw a difference of 10 bhp on a totally standard UKDM EP3 between the stock b-pipe only (centre section) and replacing it with a Spoon b-pipe (same car, same rolling road). I think the JDM DC5 / EP3 stock systems are not as bad however. The UKDM b-pipe is something like 55mm dia, and the Spoon 67mm dia.