Ok thanks for that, the car will be a mild streeter... Im currently only looking at cams & ECU at the moment with some drivetrain mods. My current exhaust is a 2.5" mandrel bent single from the catback (I will possibly upgrade to 3" however I feel 2.5" wont be a restriction at this point in time). I purchased an extractor kit so to speak, It consists of mandrel lengths, header flanges and 4-1 collectors. The size for the primaries I have is 1 7/8", I realise this is large and will possibly sacrifice some low down torque, but will this be significant?
The stock majesta headers will not fit for this conversion, hence my quest to build new ones. I am not looking for a design to support massive numbers, however something that will easily flow 400hp if I choose to go down a higher horsepower path later down the track