If, back in 1993, you asked a hip-hopper what the difference between East Coast and West Coast rappers was, they would have told you that while L.A.

and Oakland emphasized beats and lyrics, New York and Philadelphia were more interested in rhyming technique.

In California, a rapper who didn't have a lot of technique could get over if he/she had the right beats and hooks -- in the East, you needed technique to get respect.

And that technique-obsessed approach to East Coast hip-hop is the thing that defines Re-Act Like Ya Knew, the lone album by Private Investigators.

This CD is about technique and more technique -- like a bebop saxophonist who is determined to show you how fast he can play John Coltrane's "Giant Steps," these East Coast MCs thrive on virtuosity for the sake of virtuosity.

And the results are exhilarating, if limited.

Private Investigators don't have anything remarkable to say -- they spend most of their time boasting about how great their rapping skills are and how inferior "sucker MCs" are -- but the way they say it is impressive.

Although the flow-for-the-sake-of-flow approach wears thin after awhile, you have to admire their technique.

Here's where things get ironic: Occasionally, these very East Coast-sounding rappers incorporate elements of Cypress Hill's sound -- that's ironic because in 1993, very few East Coast rappers were being influenced by West Coast gangsta rap in any way.

But then, Cypress Hill was different from other L.A.

gangsta rappers in that it combined gangsta rap's thug-life themes with the sort of complex rhyming style you would have expected from the East Coast.

And even though the Investigators will occasionally acknowledge Cypress Hill's flow, they steer clear of gangsta lyrics.

Although not a masterpiece, Re-Act Like Ya Knew is an enjoyable display of virtuosity -- limitations and all.