I guess what I was asking was whether anyone actually felt an appreciable difference in the performance of the car after extrude honing the manifold.
I have noticed the sharp edges on the shoulders of the bends inside the manifold and that's what made me wonder if extrude honing might make a significant difference. Rather than paying at least $700 (incl freight) for extrude honing though, I might invest in a flexible drive and have a go at smoothing those edges myself before re-installing the stock manifold.
The engine is in a fairly mild state of modification: big exhaust and s.s. manifold (which cracked, was repaired, straightened and has now cracked again after a supersprint at EC) big Blitz front intercooler, HKS turbo (but don't know what kind as it came with the car) but it's in the standard position and set for a maximum 1 bar of boost, Splitfires and a Nistune board in the ECU. Tuning the ECU on the dyno only showed 182 rwkw but the workshop reckon it could be 10% conservative, so 200 at best.
You're right about the weight, of course, which is why spending heaps on power mods to overcome that disadvantage is pretty questionable. Having said that I really enjoy the feel of the car on the track - it will never be seriously competitive, however, and always a compromise vehicle in which I can also take my mal and my dog to the beach!