2000 8.1L workhorse with Banks Power Pack

Stock plugs are AC/Delco 41-983. As far as I know Banks kits don't use special plugs because they are only improving flow through intake and exhaust mods, not changing the tuning or fuel type requirements. You could check with Banks though....

No, but it will improve engine performance..

There are TWO engine upgrades I approve of. Banks and Ultra Power (Only one per engine though) Banks is a company with a long track record, they support their customers well and in fact in 2006 Workhorse came out with their "SS" line which is where they put on what amounts to a copy of the Banks at the factory.

Ultra Power, though not, as far as I know, as old as Banks, is about half the price and also has a good reputation of customer support.. In fact going above and beyond in some cases. That said Workhorse does not approve of UP like they do Banks. That's ok though, UP covers it.

True (short) story.. One time slice a whole bunch of folks came into one UP dealer (Who is also an RV service center) with the exact same engine failure. Workhorse authorized warranty on the ones without UP (Half of them) the other half Workhorse refused and blamed UP, note, all the same model half year, all the same failure.. As far as I know Ultra Power "Ate" the repair costs for their customers... They likely settled with Workhorse later, but in all cases the customer walked out with a Bill that said "Total after warranty----ZERO"

When I had a 1994 with Banks did not have special plugs.