You mean feel the difference.....
the M52 headers are tuned for more torque, the M50 headers are for more HP, longer length... however the distribution flow of the M52 is almost equal..
to custom it, at least RM2600.00 for a set. not cheap with 3 weeks idle. this price was it 2006 and using Jap Stainless steel 304, 2mm thickness elbows..
try calling Ramsing, he has the original HIOP headers.