PLT OF SMA SEL ACFT HAD NMAC DURING ENTRY TO TFC PATTERN.

Narrative

I WAS APCHING THE NAPA COUNTY ARPT FROM THE S AT ABOUT 1700 FT ABOUT 15 MI OUT. BAY APCH HAD JUST ENDED MY FLT FOLLOWING AND ADVISED ME TO CONTACT NAPA TWR. I BEGAN MY DSCNT TO TPA (1033). I LISTEN TO ATIS FOR NAPA AND MADE MY INITIAL CONTACT WITH THE TWR STATING MY POS AS APPROX 10 MI S OF THE ARPT WITH ATIS INFO TO LAND. THE TWR CTLR ASKED ME TO REPEAT MY POS; WHICH I DID. I DON'T REMEMBER IF I WAS ASKED TO IDENT. I WAS TOLD TO RPT ENTERING DOWNWIND FOR 18R. AT 1050 FT AND ABOUT TO ENTER DOWNWIND; I MADE THE CALL TO THE TWR STATING MY POS. THE CTLR SID I WOULD BE #2 TO LAND AND ASKED IF I HAD THE TFC ON MY R. I LOOKED AND SAID I DID NOT AND THEN AN SMA TWIN CAME FROM MY R TO L APPROX 50 FT AHEAD OF MY AIRPLANE; CLBING SLIGHTLY. I CONTINUED STRAIGHT ON THE DOWNWIND; THE TURN CONTINUED STRAIGHT ON IT'S PATH ABOUT 500 FT TO MY L THEN TURNED R (DOWNWIND) AND ABOUT 500 FT ABOVE ME AND WE PARALLELED LIKE THAT FOR A FEW MOMENTS. THE CTLR THEN RESEQUENCED ME BEHIND ANOTHER ACFT I BELIEVE SHE SAID WAS ON BASE (WHICH I DID NOT HAVE IN SIGHT) AND THEN QUICKLY TOLD ME TO RESEQUENCE #3 BEHIND THE TWIN. I REPLIED THAT I WOULD FOLLOW THE TWIN. I SAID AND 2 BEHIND THE TWIN. I FOLLOWED BEHIND THE TWIN ON FINAL IT WAS CLRED FOR AND DID A TOUCH AND GO AND THEN LEFT THE PATTERN. I LANDED WITHOUT FURTHER INCIDENT. NO ONE SPOKE TO ME AT NAPA ABOUT THE INCIDENT AND I AM NOT SURE ANYONE KNEW HOW CLOSE WE CAME TO EACH OTHER.