hi folks can anyone help me please. i have a mk2 xr2. standard engine newly rebuilt cvh . ive put on new weber twin 40's and a full stainless exhaust system. the carbs have been set up properly buy jim king auto tune. car drives fine 1st gear then 2nd it seems to be pushing back at 5000rpm 3rd gear the same happens at 4000rpm and so on and struggles to do 70mph in 5th. has a cheap facet fuel pump and a filter king regulator. could it be the fuel pump thats the problem and can anyone explain why it holds back lower down the revs as i go up the gears.all opinions wellcome. thanks nick.