if you get two close you will not be able to go as fast the o.s will get you to about 80 or more just remeber you are going to need rpms on your motor that is all you newed to do i put the cen turbo motor in mine and i put both genisis gears on first and second you do need to demmel second out just a tad but a 10 year old could do it and a dremmel kit is only 20 dollars i hit 87 mph's on two different radar guns and we calculated the speeds with a 100 foot pass about 50 times honestly to hit 100 you would prob need a modified 21 capable of at least 50,000 rpm's i was thinking of taking my 4tec motor and puttin it on the cen i have the 2.5r but i know the power band is only like to about 18,000 but i still might give it a shot the cen was the right way to go the only thing about a new motor you need different clutchbell and all and maybe you can get like a 15/20 or more i now cen makes interchangable spurs now so you might want to look into that i might try that and supercharge my motor so i will still have some ponies to make it to about 90