all manual bleed boost controllers have this problem, you will also find that you get more boost in higher gears.
the solution to put it simply is electronic boost control,eboost for example
i can make you a manifold that will exceed your expectations,but fitting it to the factory location is impossible.
if you must stay in the factory location,use the factory manifold and be happy.
lol you pm'd with with only an answer of where the ficticious royston vasey is and where i could possibly buy it on dvd! lmao
where are you really located?
if you guys are stil chasing letters your best bet is to draw them up on cad and i will put you intouch with a very well priced lasercutting mob that will do the job no dramas
run a 4" dump pipe and turn it down to 3.5" at the bottom of the firewall.
the gate needs to plumbed back so as to cause minimal interference to the flow of the exhaust.
ive got a pic somewhere of one i recently plumbed back, ill dig it up