This a new factory built S400 turbo, it is also referred to as a B2 turbocharger. This turbo is commonly used as the bottom turbo in staged turbo setup for a cummins turbo diesel. It is capable of moving more air than an ht3b and spools as quick if not quicker than an ht3b 26. The B2 rotates the opposite direction as an HT3b so if your thinking about replaceing your ht3b with this your going to have to replumb your twin setup. In properly setup twins this turbo is capable of supporing 650-700hp.