The time has come to replace the pathetic std manifold on the corsa along with the redundant secondary air injector valve. The obvious choice would be the SBD manifold as it was designed for the TB kit on the car. However I have been told that this manifold is primarily designed for top end performance, and can cause a loss of torque lower in the rev range, which is not ideal for a road car. The other option is the lexmaul manifold which is a 4 2 1 design which gives less top end power, but allegedly more torque and may be more suitable for road car use. It also has connections for the std manifold heat shield and lambda sensor and is supposed to be easier to fit than the SBD unit. It is also slightly cheaper and easier to get a hold of (there always seems to be a huge waiting list for the SBD one). Does anyone have any experience with these manifolds or suggestions as to the better option.