Well for starters I put in the HEI tonight but its definitely off a tooth or two because it fired right up but popped and sputtered. Also the coil I got says from 4000-7000rpm. I talked to some mechanics and they gave me mixed advice. Some say it wont work well in any other rpm but that and others say that it will work just as good as a regular coil but better between 4 and 7k. I looked online and it says I can use the Mallory Proform box, which I have from the old setup,in conjuction with this 4000-7000 coil but I dont want to unless I have to. Any advice is appreciated.