I've got a greddy evo catback but the previous owner welded his homemade exhaust to the stock flanche and welded the flanche bolts and so one of the options i'm exploring in putting in my evo catback is getting a new cat as well... my cat is pretty old (stock '95) and is a bit rusted. So what do you guys think? Should I get a high flow exhaust? Those are surprisingly cheap, like $40-$50. Or get a new stock cat? Do high flow cats improve/de-prove anything? I mean If i have a 60mm catback on it would a high flow cat let it flow too high and cause me to loose too much torque? Are there any other ways to solve my predicament? Any suggestions would help (including links to good CATs etc.) Thanx

 

though i've never checked it out, chances are the oem cat will actually cost more than a hi-flow one. as far as not having enough backpressure, as long as you're using 2.25" you'll get better flow with the cat, and not so much that you'll lose alot of power. expect to lose a little low-end torque regardless or whether or not you put a hi-flow cat, that's normal and will be made up for by more top end horsepower.

in short, get the hi-flow cat, it'll probably be cheaper anyway. gains will be minimal, but they'll be there.

 

so either cat i get the flow would be about the same? Just wanted to make sure... And also would a high flow cat sound too loud or make the nice sounding evo exhaust sound... bad?

 

high flow cat will only make things louder as far as sound. As for performance, our accord's stock cat is very poor flowing from our tests at the shop....so if you can get rid of it, do it. I'll try to dig up the flow test results at some point.

- Nathan

 

how loud is louder? And also I heard that the evo catback sounds really nice... would the high flow exhaust make it sound bad? Hehe sorry for sooo many questions but i wanna make sure before i spend the $$$. Thanx

 

eh, I'd say 1-2 db, but if you know anything about db, each db is twice the volume of the previous if I recall correctly....so for the EVO, probably a little over legal limit over in CA

 

Ok so i've kinda decided to get a new high flow cat... i saw the ones from a link someone put up earlier... http://www.car-sound.com and http://www.magnaflow.com ... those look pretty expensive and are only universial ones... at least i couldn't find the direct fit for a 5th gen accord... but uh that means i'll have to pay someone to install it since i just quit my job at the autobody shop today... i don't have a lotta money... are quality of high flow cats that important? If i had a bolt on $40 cat from ebay would that make that much of a difference than getting a better one? If so how much difference? Thanx

 

Try http://www.ketronsales.com.

They are based in my town. Pretty good guys. Ketron has some direct fit hi-flow cats. Might be what youre looking for at a decent $.

 

here some point i want you to know before blowing your money.

-if your cat is still working=dont fu-k with it
-if your state got those emission control thing=dont fu-k with it
-adding hi flow cat Might give you cel
-adding hi flow cat might get you a ticket
-when you add a hi flow cat your car's exhaust tone will change, it wont just get louder and sound exactly the same way.
especailly when vtec crossover you might get some annoying raspy sounds

 

Actually he doesnt have the O2 sensor behind the cat, so he shouldnt have to worry about the cel.
True dat to everything else though.

 

My friend bought one of those cheap cats from ebay, and they dont have any holes for the O2 sensor. So A, you will drive around with the O2 sensor disconnected, or B pay the average mechanic a few more bucks to make that O2 sensor for you.

Hope it helps

 

you sure? obd2 right? it should have two o2 sensor, one in the manifold and one in the cat.

anyone know for sure?

 

Yeah my friends cat was installed into a 97 accord, which has OBD2. Those cheap cat. converters on EBay dont have any holes for the O2 sensor, and those that do cost around two hundered dollars. I guess one is better off buying the 50 dollar unit form ebay, and they letting a mechanic drill a hole. This is what my friend did, and his engine light isn't on.

 

Yes, if it's OBD II then it will have a O2 bung on the cat. as well as on the exhaust manifold. I have a Greddy Evo on my '96 Accord with a 2 1/2" inlet/outlet Carsound cat. It sounded great and gave the car a little more power (nothing to put you back in your seat, but still some power). The car didn't sound much louder at all, but has a nice mellow, but noticeable tone. IMO, get a Carsound cat. and have someone weld the flanges and O2 bung on. It only cost me $100 to get one fabed up and put on.

 

in my experience an aftermarket cat will eventually give you cel's for low efficiency catalytic converter. i think it would be alot cheaper just buying an o2 eliminator to kit, or doing the wiring yourself to avoid any cel's in the future.

 

although for 95blk2draccordEXMT they wont have to worry about the low efficiency cat cel, o2 eliminator kit, or an o2 bung for the o2 sensor, as the car in question is not obdII and has no second o2 sensor.

 

Ah yes, it's a '95. However, with that Carsound cat. I had, my CEL has never come on yet, and I have had the cat. on for about 7-8 months already. Another thing I have found to be awkward is the fact that the O2 sensor does not need to be screwed into the cat. For example, I had a test pipe before I had the high-flow cat., but I never welded an O2 bung onto it. I left the O2 sensor connected and zipped tied it to the heat shield on the bottom of the car. I drove the over a year and the CEL never came on. Go figure! Yet another Honda phenomenon!

 

Yeah, you don't have to screw it in. Mine's just welded into the pipe after the cat.