You will be okay as long as you don't get to greedy with the spray. I assume this is an adjustable kit? Is it a dry or wet kit? I sprayed on mine, got greedy with the juice and fried a piston ring. Reason for the new stroker. Just remember that you need top back off the timing with the juice. If you don't have one, I would suggest a Steeda Timing Adjuster. Its easy to install and will allow you to retard the timing with little effort. No timing light is needed with these adjusters. As a rule of thumb for juice, gap the plugs at 35, run a step colder plug, and back off the timing 1 degree for every 25hp shot. Example: 75 shot of juice, back the timing off 3 degrees. Mustangs run a tad lean from the factory, so, make sure you have the proper ratio of fuel/air so as not to go lean and fry a piston or ring like I did.