don't breathe the stuff that comes out, carcinogens

 

loose the cats if you can, made a huge improvement on my car and i had bonew highflow, i never felt the car with the tock cats i can't imagine the diff it'll make

 

You could make a custom header, or you can pick up a pacesetter that will bolt to your stock cat. When you remove your cat you will lose a lot of low end torque (which can really suck since you have an automatic) then your 5/6 ports wont work right and you will have no high end power either. For now though, you can gut your two presilencers for a little to nothing gain and it wont affect your emissions. I suggest gutting or replacing with a straight pipe, the main cat, when you are converting to a 5-speed.

 

i have a 91 n/a automatic i am going to be taking off the cats but i dont know what to put in its place i dont want to mess with the 5th 6th ports will 1 bonez high flow cat work and replace the second cat with a straight pipe

 

i have a 91 n/a automatic i am going to be taking off the cats but i dont know what to put in its place i dont want to mess with the 5th 6th ports will 1 bonez high flow cat work and replace the second cat with a straight pipe please answer some one that knows the for sure answer

 

My car sounds really good with a straight pipe, and not to loud.

 

did you replace both cats with a straight pipe or just 1 also did you have any engine mods or problems with your 5th 6th ports opening

 

I did mine by cutting one side off, pounding all the crap out, and welding it shut again, That was easier for me...later

 

would 1 high flow cat make the 5th 6th ports work and put a straight pipe for the 2nd cat

 

why wouldnt i? get infront of some punk as ricer at night and simply rev it. he wont wanna eff with me after that.

 

I have a S5 with the port sleeves removed for better top end, streetport, and a racing beat header to true duals with straight pipes to the HKS muffler sections and it sounds beautiful. I suffer no low end what so ever infact I have an lsd and I can't stop spinning in first and I always go sideways in 2nd! It's not to loud at all sounds quiet infact until I open the throttle up. I think it's because of the quality of the HKS 50mm mufflers...they're solid you can't tap on them and hear a noise, it's like knocking on a rock! I also get very long and nice flames coming out at night as well.

 

i got a stock s5 n/a can i replace the first cat with a high flow one and replace the second one with a straight pipe i wont suffer any problems with my 5th 6th ports or anything

 

hmm, basically. but i have had rb headers, presilencer and catback, and im very very pleased with it. my car runs a small bit on the rich side of things, so the exhaust smells extra sweet and if i punch it a little bit and it happens to be night time, i can see the flash in the rear view of the '***** of fire' that come out of the pipes...someone described them as sort of molten looking ***** of gaseous fire...love it. oh, and its incredibly loud...if the windows are down it rings in my ears and people flick me off when i go past...its pretty amusing. but the whole racing beat exhaust will open up the airflow very nicely in the fc, and i havent had any problem with the 5th/6th ports not opening.

 

yea i know the whole exhaust would be great but it would only be for alittle bit because im doing a tII swap so since its stock it would be better to have a high flow cat and a straight pipe for the second cat THIS WOULDNT GIVE ME ANY PROBLEMS WITH THE PORTS OPENING RIGHT? ........... also i know the heat would destroy a high flow cat but i forget where to get a high flow cat made for rotary engines can i get a link to buy one

 

I removed my primary cat. and replaced it with a stock pipe from a S5, gutted the secondary cat. and gutted the main cat. The exhaust is stock except for the gutted cats. With gutted cats. and no mufflers, just the Y-pipe, the car was LOUD. The secondaries open fine, but I routed the air pipe back to the main cat. since I retained it after gutting it. To gut my cats I just used a decent sized sledge, and a crow bar, a tire iron, and whatever else was long enough to jam down in there to remove the ceramic, or whatever is in them. I replaced all the gaskets, and used silicone sealer too. If you stock exhaust is in decent shape, this is probably the cheapest thing to do...

 

so theres 3 cats all together

 

Ok, so by gutting the cats, you aren't loosing back pressure? If this is the case, I was kidna thinking maybe removing the first pre-cat, gutting the second, and adding a silencer in place of the main cat might be the way to go. I don't want to drive the neighbors nuts, but after some consideration, flame shooting wackiness sounds great to me.

 

I used to have straight pipe all the way back on my 87 N/A. I just wanted to try it, and let me tell you...it is LOUD and it sounds like ***. Its not even a nice loud sound...its more like a huge gargling fart at lower RPM's, and it sounds like a pencil sharpener on crack at redline. 2 days later I put the exhaust back on.

-Joe

 

lol @ pencil sharpener on crack. Does gutting the cats basically have the same effect as just putting a straight section there, or do they cause turbulance and deaden sound still?

 

No, it doesnt. Its not a even good shape for flow. Just make a streight pipe and bolt it on, seriously. Dont destroy a perfectly good cat!


PS: Hey, just mail me your good cat and I'll mail you a streightpipe the same lenth, hows that?

 

so just 1 high flow cat will be enough for back pressure and not worry about the ports not opening and replace the other 2 cats with straight pipes? please answer quick thanks

Nate

 

doooooooo ittttt

 

ok thanks everyone but where do i find the high flow cat made specifically for the rotary engines and which cat should i replace for the high flow cat on the closest to the manifold the middle one or the rear one

 

On the punching out a cat. No pun intended, I'm just wasted right now. I used a drill and one of those paddle bits. The ones that are flat for making big holes in wood.

 

ok thanks everyone but where do i find the high flow cat made specifically for the rotary engines and which cat should i replace for the high flow cat on the closest to the manifold the middle one or the rear one
anyone?