I'm in the process of assembling my engine, and I wondered if anyone have any info about throwing away the stock precat for a 3" downpipe without otherwise changing anything else. Will the boost creep to any dangerous levels?
All info is appreciated The car is bone stock.

Also I'm gonna get a new clutch, I've been thinking about the Exedy stage 1 on they got at MazdaTrix. Is it any good? What power levels can it safely handle? And does it fit the stock flywheel?

 

If you're keeping a main cat and the stock catback system, you should be fine when it comes to keeping boost at stock levels. Just keep in mind that none of the stock parts are 3", so you'll run into problems connecting a 3" DP to them.

Exedy is a good clutch brand. "Stg 1" clutches are usually good for ~300 ft. lbs. of torque, but you'll have to find manufacturer specs to know for sure. Check the Mazdatrix site to be sure it says it's for a TII.