Is there any negative effect of ignition booster system (such as msd, jacob etc etc) at leading coil??

I know they cured break ups @ higher rpm and prob better fuel millage...

 

In general, you're not going to see a huge benefit unless you are running high boost and rich ratios. The stock FC system is quite strong and is often used as an upgrade for other vehicles (like FDs).

In my opinion, the single largest benefit from a CDI box is that it makes it VERY difficult to flood out the car.

 

Thank you aaron. Its a good thing that with CDI box...you can't flooded an rx7 (or rather difficult to flood an rx7). But i am looking for con's...

Any reason why you should not use a CDI box??

Everytime i ask my engine builder, he always told me that i dont need it and its a bad idea. He never give me a reason why.

 

The negative effect is that it removes money from your wallet while not always providing a gain.

And MSD stuff has had some reliability issues in the past.

 

don't get an ignition upgrade unless you are getting spark blowout even with fresh plugs.