.....and it made a huge difference!I was having trouble with my turbo transition after removing the air pump,but now both turbos spool great . It made a big difference- like night and day . I think my next mod will be tires...the ones i have now wont last long!

 

do many people have problems with transition between turbos with air pump off?

 

with the cat still in place and no airpump he was probably getting a bad transition cause the cat was becoming clogged. gutting it fixed the clog, therefor fixing his transition problem

 

I suspect a clogged cat so how do I gut it? Mine glows cherry red after 2 minutes of idleing and the engine runs weak too. Exhaust does come out the pipes strong though? Bill

 

*pull off cat

*knock all the inside **** out

*put cat back on



Be aware that you will now have a restrictive midpipe and might get boost creep or run lean. Do you have any mods?

 

Actually, it's not that easy. When I gutted mine, I had to saw it open, and painfully pull out the chunks of metal and ceramic crap. I first tried to torch it open, but what ever metal mazda used splatters (not good). It welded up nicely though.
It did make a difference in spool up time, and I hit fuel cut in high altitude, so yes it has boost creep. The nice thing about this mod is that it passes visual. On that note, I have also thought of transfering the precat heat shield to an aftermarket downpipe to pass visual. How to do it, I don't know.

 

I was wondering how long it would take for the cat to clog but i only ran the car a few hundred miles. I know I was running rich but apparently thats all it took,anyway,I did'nt have to cut the cat itself open , I just used a long metal rod attached to an air chisel.It took about 15 minutes after the cat was off.It has a pretty good tone now with the stock catback.I started to buy a midpipe,but alot of guys with strong turbos have to install restrictor plates which seems kind of redundant to me,and more expensive.I did however just get a ticket for careless operation because my tires dont hook up very good now-cops dont like that.But i also notice how my clothes smell like fumes.Oh well, the price we pay.....

 

Excuse me, but what is boost creep?

Ant

 

https://www.rx7club.com/forum/showth...ht=boost+creep

...only took me a minute t search and find this so search a little next time.

 

Are there any significant differences in performance between a gutted cat and a midpipe?

I do like the fact that a gutted cat will pass a visual - even if a cop knows that much about cars.

 

there is a weight issue. the stock cat wieghes a ton whereas the mp or a hi flow cat for that matter wiegh a lot less. Also there is still some turbulence with teh gutted cat so if you went with a mp you would pick up a few more hp.

 

Any flames???

I just swapped my cat out for a high-flow, but I'm hanging onto my old one in case I ever want to go this route....

 

ttpowerd,

would a fully gutted cat weigh that much more than a midpipe? Once all the innards are removed, I would think that the shell would weigh only a few pounds more than a midpipe. Am I missing something?

I hear you on the turbulence thing.

Also, anyone run into problems with the collection of water in the gutted precat (like a muffler) causing it to rust out?

 

I have not gutted a cat, never picked one up, so I don't know about the weight of the gutted cat but the stock cat does weigh a good bit more. You are right that it will be lighter but still, compare sizes, stock cat is big whereas the hi flow or mp is relatively small. Plus the stock cat has that gaurd on it and stuff. I would say that a gutted cat probably weighs 8-10 lbs more than a mp.

 

you CAN just beat all the **** out of it with a long *** pole. just make sure you get it all out, or it is going to rattle like a ************. no cutting or welding is necessary.