just a quick bit of advice.on the rx7 fd3s twin turbo your mods are limited. you should upgrade your engine management right away although you can push to air filters , Cat back exhaust and intercooler. After these 3 mods have been installed you MUST install an Aftermarket engine management system Eg: Apexi PFC , Haltec , F-con Gold Pro, Which can allow you to upgrade to Single turbo, De-Cat , Bigger Fuel system etc etc many more mods but remember! DO NOT REMOVE THE CATALYSTIC CONVERTER ON AN RX7 RUNNING WITH STANDARD ENGINE MANAGEMENT.
If you do you will result in over boosting due to faster air flow from the exhaust and hit fuel cut on the factory ECU and detonation you engine quickly resulting in a costly engine rebuild. If anyone needs Rx7 advice just ask. Thanks