I'm not sure if there is a way to tighten them but your cables should be fine it's just that dsm shifters always feel kinda rubbery. You can buy some symbroski (sp?) bushings (only place to get them now is machv.com), or do the free mod which is made of just washers that replace the rubber bushings, but symbroski it is better and only about $20. Machv also sell stiffer bushings that replace the ones where the cables attach to the tranny.