Bolt between manifold and cat busted; Should I replace with High Flow Cat?
 

I was removing the stock midpipe/cat at the manifold tonight (dropping tranny for RB flywheel, PP and HD clutch disc) and one of the bolts sheared off. grrr. :mad: It looks to me that the bolt head is spot welded, effectively makeing it a stud. I could try drilling the bastard out but I also could take this as an opportunity to replace with a high flow cat.

The new pressure plate and heavy duty clutch are intended to harmonize with my, as yet unordered, greddy turbo. So a better exhaust flow would fit the theme. Is this reasonable? The major problem is that I have a RB exhaust already installed. It necks down at the cat to match the cat pipe size. Wont I have to replace the RB cat back (which I really really like if only for the sound) to eliminate the neck-down? (yes I have read the posts on RB's opinion suggesting their exhaust is not suited for a turbo. My opinion on their opinion is "bull$#i+!")

If not, which HF cat would mate well with the RB catback and the future greddy turbo kit? (is there a turbo back out there?) No I do not want to delete the cat and pollute the air and possibly fail sniffer tests (in MD near DC. My other car has gotten the sniffer treatment dispite being a '97)

P.S. if anyone cares, the flywheel swap seems doable on jackstands. Dont attempt if you are closterphobic. :eek:

Be careful. Rudy8 & I have had issues with the hi-flow cat unit & the Greddy turbo kit. We have had some backfire issues. In talking with Benny (Greddy) the kit/tuning was never designed for a high flow cat. In taking off his high flow cat Rudy8 got rid of quite a bit of his backfire. May have to lean out the mix a bit more.

Carbon, I can tell you from firsthand experience that not only is the flywheel swap doable on jack stands but also with mere hand tools and a 3/4" breaker bar for the flywheel nut. I did my own swap, then drove to Atlanta with all the necessary tools in the trunk of my RX-8 and did a swap with rxeighter in the parking lot of Marietta8's own shop. Piece of cake.

CRH

Took about 5 hours -- and no extra parts left over! Thanks again Charles for leading the flywheel install.

I'd go with the high flow cat, unless the turbo is mere months away.

Don't go with the high flow cat unless you instal one or two resonators.

It will be too loud for you.

Thanks for the all the advice. It looks like the better idea is to repair the stock cat.

I would like to be able to use the stock maps that come with the emanage in the greddy turbo kit. I dont want to start tuning until much later (maybe after adding bigger injectors and a fuel pump). Sounds like the high flow cat would require immediate tuning that I am not prepared to do.

With luck, the car should be down off the jackstands tomorrow.

Razz, how loud are we talking (just curious)? With the K&N intake and the RB exhaust at WOT the car already screams (a good scream in my opinion, like the battle cry of a samurai. Kurosawa should make a mazda commerial :rolleyes: )

Tho I am hoping that the turbo will make it quite a bit quieter as it interupts the direct path from the intake to the port and stops up the exhaust a bit.

any welding shop can replace the bolt if you provide it, it's likely metric stainless steel

Check out the RP high flow CAT sectionhttps://www.rx8club.com/series-i-aftermarket-performance-modifications-23/rotary-performance-super-cat-midpipe-54033/