lol doesnt sound like the kind of power that will push you on to 120mph though.... you were beating him right up to the point where aerodynamics becomes more important than weight, and only 5-10hp difference can give you quite the edge then (5-10hp which would have been just about compensating for the extra passengers).
(standard 1 litre will just kiss 90... 1.3 will end up somewhere 95-100mph, a 5mph difference can look like a lot when you're on the losing end of it... and the mk3 would still go up to the high 80s alright when rammed solid with gear from emptying my university room, just took forever to get there and suffered on the hills)
but it had *some* effect at least, so probably worth it if you're dead set on tuning up a mousepower engine like that

(like i was when i bought the chip

)