I want to reduce body flex, and a brace between the towers is the logical approach as on the latter Gens. The problem is that a stock air filter gets in the way.

What is the solution for a stock set-up?

If I change to a K&N or RB filter what are the options?
Are these filters too noisy for a street car?

 

No.. http://www.sdjmotorsports.com/FlowPls.htm
The BEST filter you can buy.. a bunch of race car drivers use them on their race cars, my race car has it on it, and it also has a strut tower bar going across, it fits fine.

 

I picked up Jim Susko (Nation Champion in an Rx7) First Gen set up manual and he does no advocate for a from strut tower brace. I know everybody and their brother sells them, but how much flex do you really have?

 

Lots of ITA guys use them. I've seen Spec7 racers take them off saying it makes the car understeer. But that class doesn't have the flexibility in chassis setup to make adjustments to suspension and make it work right.

On the other hand, I had metal plates welded around the tops of the strut towers and custom brackets welded in and a very tight fitting brace bolts in there, triangulating at the very strong horizontal body lip on the firewall and tying into the roll cage. The greatly reduced chassis flex does make for a more precise and consistant handeling car.

http://fc3s.org/dcp00676.jpg

And don't buy one with heim joints. They twist. The idea is to have a solid brace. The one MazdaComp and Mazdatrix (used to?) sells is too flexible.

BradP