Does anyon know if it's poss to tune / de restrict a gilera dna 125?

i have a dna 125 and wanna use it on motorways have full car license so can, but just bout does 70mph, i know you can tune it but i don't wanna spend £1000 just to get an extra 15 - 20 mph is there any other way without spending more. it's a 2003 4 stroke liquid cooled one!