yeah, i've heard less than stellar things from the people's pipe but its always the case when people cut corners on a cheaper pipe they tend to cut corners on the tuning. some of the comments i've heard are that it has that 'boss' style hole in the midrange... makes sense with a big header and sorta similar chamber.
the old mk65 with a estoril or proma was a midrange monster, from like 5k to 8k it would stomp... pretty much all done by 9,5k with stock porting. even with a biturbo it held its own in the mids. if the port map is the same i'd be suspicious of the atomizer/needle/pilot jet combo. those damn phbg's don't really four stroke to tell you what they are doing.
or just push the 'easy' button and throw a VM18/ 20/22 on there haha
oh wait I forgot you're pretty much committed to the dellorto haha