Realistically, we all have that "off the shelf" suspension and having Megan/K-Sport coilovers doesn't put one lower than you. Just because a product is not the top brand doesn't make it inferior or unreliable. Also, by the looks of the pictures and work shown the setup seems in no way unexecuted because it takes a lot of work for a custom manifold/turbo setup.

There is no fault for the OP to want to have the lowest cg as possible, even though he doesn't have an F1 car, so since he doesn't own a professional formula car I don't think he has to use the most expensive raved suspension products there are as well.