The only way I would ever use tubular manifold on one of my cars is if a cast manifold was not available for the job. One of the most important jobs of a turbo manifold is preserving exhaust energy to drive the turbine. heat lost from manifold is big problem with tubular manifolds. they put tremendous amount of heat into engine compartment. engine bay temps can sky rocket. intake temps at filter go up with it. the evo world has done extensive testing in replacing stock manifold with tubular. take a close look and 95% of manifolds tested lost HP. and this was quick dyno pull test. add engine compartment heat and increased intake temps (not in evo testing) and test would have been far more revealing. stay cast if you can. I have a nice manifold for cheap for you if you are interested send me a PM for details