This is a slick organization. They have very expensive marketing materials, and their sales staff lull you into believing your project will be completed on time, on budget and to your satisfaction.
That is far from the truth. The budget estimates they provide are not realistic, and you will never be able to build for what they tell you unless you use recyled materials and low end fixtures (i.e. they told me I would be able to buy and install all fixters for 2.5 bathrooms for $5,000).
Although they provide the exterior shell and indicate that you can use any contractor (i.e. theirs or one of your own) - after an exhaustive search, I discovered that I could not find a contractor that would work on Modular Home Additions. So I was forced to use a Modular contractor. He eventually abandoned the job and we were forced to find independent contractors to complete their work.
You need to keep an eye on Modular. They try to take short cuts, and if there is a problem, I advise you to hire an independent inspector. The owners use bullying tactics to back you into their solution.
I believe we made a mistake in selecting Modular. Don't make the same mistake