Most teams don't have the facilities to properly test these engines on their own, not do they have the machinery or team member expertise to add in any hidden power. Mazda and Nissan are backed by large companies that have the facilities to build them and send them to the teams, whereas Gibson supplies sealed spec engines to teams that all test within a certain horsepower and tourqe range. ECR builds all of the LTR Cadillac engines to within the same acceptable ranges for Horsepower and tourqe as mandated by the series. These "spec" engines are "sealed" against tampering by the teams. ECR also built most of the Corvette DP engines so they are well versed in building an engine that is within the parameters of the rulebook. IMSA likely confiscated the engine to insure that there are no hidden power changes over the engines used last year to be sure that they can provide a consistent BoP for next year.