I love the look of Opti-Seal but I would like to know what would be the best product to add extra gloss without losing the OS look? Should I go for Optimum Instant Detailer & Gloss Enhancer or Optimum Car Wax.

Yes

Thats the correct answer for sure! OSW covered with ID, and washed regularly with ONR

Ash - they do slightly different things IMHO. OCW adds loads of gloss but a slightly warmer wax look. OID certainly adds gloss but obiously doesnt last quite as long. They're so cheap that I have no issue recommending both.

Thanks for the help. looks like it's going to be both then