Its the same as Blitz and HKS spark plugs.
They dont make them, they source them, slap their logo on it and onsell them.
Id like to bet that they dont make their own silicon hoses too.. see what im getting at?
And as above, Denso make great products. I recall pulling to pieces my old ITR when i 1st got it, half the stuff that came out had Denso on it, plugs, radiator etc etc. They make alot of OEM stuff, so it has to be fairly decent right?