>My guess is it's simply a matter of vacuum hose material. Actually the hard nylon hose just kinks easily and doesn't un-kink very well. It will maintain its size much better than silicone hoses, though. (It will not shrink or expand.) Just an FYI but Autometer boost gauges are notoriously inaccurate. I wouldn't trust one at all. (with gauges you get what you pay for.) -Jay