My wife and I are buying an in-progress spec home build and customizing it to suit our needs. Unfortunately, the builder is forcing us to use his vendors for most everything. One of the problems we're running into is fixtures. This guy is insisting on us picking Delta brand faucets. I hate Delta and want Kohler but this guy is saying that the plumbing that has been installed is incompatible with Kohler. This sounds like bullshit to me, but I have no experience and can't say for sure. We're considering just spec'ing builder-grade faucets everywhere and buying the high-end Kohler that we want and having a plumber (or DIY) do the install. Do any of you guys have experience in this area? Is there really such a thing as vendor-specific sink faucet connections?