what kind of ignition are you using?

Stock ignition on the fd is fine up to at least 20 psi. I run ngk 10.5 race plugs however.

i was lookin at the hks twin

I have the hks brand new never installed but thinking i should go bigger.................It is a nice set up for what i have seen but im wanting some other features now that i can only get from a msd set up..............Mine might be for sale if i can get my money back outta it.......................

let me know how much

Keep the HKS. the msd igntions only work on two of the plugs, the leading I believe but the HKS works on all four plugs giving you the maximum spark. I thought the same thing but was set straight by my shop. Call Pro-Tech Performance in austin tx, they specialize in rx-7 and the two owners both have one, one running 650 horse and the other around 580, they're pretty good lol. number is 512-834-8771.