357

I want to run my car without cats (especially after doing the ATF treatment), but since I don't have any money to spend on buying an RB replacement pipe, I'm thinking about taking the hack route, and just punching out the **** in the cats. I've heard this works. First off, how hard is this to do? Second, what will be the change in the tone and volume of my exhaust note (at all rpm's)? Third, and lastly, how much more power will i get out of my car (completely stock engine), and what will this do to my fuel economy (i'm assuming it'll stay the same or go up, but i could be wrong)? Thanks, guys.

White84SE

I did the RB replacement pipe, but you should have about equal results as me. Hardest part of this job is getting the old cats off. Fortunately my car was fairly low milage so it wasn't too bad, but the more miles they've seen, the more difficult it is. The car is a good bit louder now, but not completely obnoxious. It's kinda funny, while it does have a little bit of that rotary chainsaw-on-steroids sound, it's also deeper as well. As far as power levels go, again, depends on the condition of the cats beforehand. If they were ugly and plugged up, it'll feel like a you've strapped an extra motor in. If they're not too bad (like mine) you'll get a little bit more but nothing earth-shattering. FWIW, my gas milage dropped one or two MPG right after I did this, but I attribute that to a suddenly heavier right foot. LOL But now, I've got about 2-3 more MPG overall..

--Danny

specRX7_22

you asked how hard it is to do...... not very

just stick a crow bar or other long metal object in there and break all the little screens and they will fall out. the sound shouldnt be too bad cuz you'll still have the pre-silencer and muffler. on my road race car (which had ONLY a cat) there was a noticable difference after removal of the cat.

--eric

357

thanks for the info, guys. My main concern is that the car will have that hollow-sounding "braaaap" tone to it, like a riced out honda.

White84SE

If you've got the stock muffler, it'll sound more like a large displacement two-cycle street bike...

--Danny

85RX7GS

iTrader: (1)

Do you have smog inspection out in Nebraska?

mazdaspeedrex

No, we don't care about the environment out here in corn land. They used to have county inspections but that stopped in the late '80s. I've run my last to cars with out emissions and no one cares. Except for the louder sound maybe.

357

How large are you talking? I have a 1974 Yamaha DT250 Enduro (250cc 2-stroke). What kind of bike were you thinking about (just for reference, I know exactly what a 125cc motocross bike sounds like too, cause my friend has two that we ride)?

White84SE

Cross a 500cc two stroke (a la Honda CR500) with a 400cc or so 4-cycle... if you can imagine it, that's about what it sounds like... sounds are hard to describe...

--Danny