I have a 353 fastec with the 600sci's and the set back boxes and the best speed I have seen is 86.9. I think the props are not giving me enough lift but I'm looking for suggestions?? I am now running the stock 5 blade mercs. I want to be over 90.....

wow I am at 81 and some change with my 353 500 efi's and 27 five blade stock hydros no boxes. I would call throttle up and ask for help.