bigreed91

I got a 1990 rs 305 tbi, i recently purchased a set of hooker headers and 3" y-pipe. I havent put it on yet cause i still dont know what to run with it. First off though i wana get rid of the cat, so what did yall do with the o2 sensor? Also did these come with 2 o2 sensors or just 1? Once i find out how to lose the cat how does a single 3" pipe into a single 3" inlet dual 2 1/2" outlet sound? Thanks in advance for the help.

torque_is_good

youtube.com has a gazillion sound clips of exhaust. Your question about how does single in to dual out should be rephrased to read

how does the generic makeup of almost every single aftermarket system which is configured the same as the stock system sound? I'm not trying to be a wise guy but this topic has been beaten well to death. The search feature and youtube are your friends. yes, you are excited and enthusiastic but search and ye shall find.

what to do with the single O2? Your headers will have a place for it on the drivers side or you will need to have one welded into the header.

bigreed91

sorry i didnt mean how does it actually sound, i meant more of is that a good setup.

fireturd350

iTrader: (8)

Against federal law to remove cats on street driven vehicle. Also not a good idea if you have emission testing.

Single o2 sensors on ours normally mounted in driver side header/manifold. Some people do mount them in the merge of the y pipe if they have a heated o2 sensor.

torque_is_good

some states such as FL have no emission testing.

BlackenedBird

iTrader: (5)

Doesn't matter. That only applies to State Inspection, meaning they don't test emissions output. It is still a Federal Law to have them. State Law only apply to testing the output, when it comes to non-emissions testing, not the presence (or lack of) the emissions parts.

bigreed91

i just figured id lose the cat considering as soon as i pull the a.i.r. pump off it wouldnt pass a visual inspection anymore, which is why me being stationed in virginia where inspections are required i registered my car in my county back in tennessee, so i could do whatever to my car while im here

fireturd350

iTrader: (8)

That's just fine you can bypass inspections that way, but Federal Laws take priority over State Laws. You could still be ticketed removing the equipment, so keep that in mind.

I believe in Illinois it's ticketed per devices so since my car had 2 cats stock I could be looking at 2 fines if I removed them.

They do make AIR less high flow cats.

92RS_Ttop

iTrader: (3)

Which wouldn't really do him much good as far as emissions inspections since the AIR system is also required by federal law, same as the cats.

FWIW, in PA cars are exempt from emissions inspections if driven less than 5k miles/year, or if registered as a classic or antique.

To the OP - All thirdgens came with only 1 O2 sensor mounted before the cat if they had a single cat from the factory. Not entirely sure about the dual-cat cars.

When I still had the V6 in my Camaro, I hollowed out the cat and reinstalled it to pass the visual emissions inspection. The honeycomb inside was all broken up and clogging up the exhaust and I knew I would be swapping out the engine and exhaust in a year so it wasn't worth buying a new cat for one year. After I swapped to the V8, the car fell under the 5k/year emissions exemption so I switched to a true dual exhaust with no cats.

Recaro trans am

iTrader: (1)

The power gain with a cat removal would not even be noticeable on a 305 tbi. Do your self and the environment a fav and just put a high flow cat back on. Does not require the air system, and the exhaust wont burn your eyes. lol

With that said I'm a hypocrite. I have no cats since my custom dual set up would not allow it with my lowered car. Been looking into replacing them now that my exhaust sits higher and I now have coil overs.

bigreed91

Thanks for all the input, i wana try and get my exhaust done in the next week or so, i may just go with magnaflow highflow cat just cause ive seen em at advance so no waiting on an ordered one and it was only like 70 bucks

NathanLewis

I ditched the smog pump too. And I live in virginia. I still passed inspection. Just depends on who you go to but some guys will let a few illegal things slide away

CanuckBird

headers,no cats into true duals/flowmasters www.youtube.com/watch?v=VmDPMPEh9Js

ninetyone

iTrader: (2)

Yes, keep your cats on there. Not much of a difference anyway.

Shane B

Im running single three inch,no cat and a flowmaster.I love the sound and I dont get the bad smell that some people have referenced.It didnt give me any performance gains.I live in california but i have a house in arizona so its registered there.As far as the o2 sensor,I didnt have to mess with any sensors.I hallowed out my cat.There were no sensors behind the cat on my car.No SES light on.

Austin19

In alberta, canada, its completely legal to run a car without a cat. I tried, didn't like it. The smell was bad, and there was really no noticeable power improvement (however I have a full stock system so far, so the brutal LG4 headers are probably holding the engine back more than a cat ever could).

Gallileo60

More people than will admit..lol....It sounds great....O2 sensor is not near the cat..You do have to remove, or plug the AIR line...My headers had a bung already in for the O2 sensor, if not you will have to buy, or make one, and have it welded in the pipe as near, or a bit closer than the stock location, unless you wrap your headers, and pipe..(I wont open that can of worms tho)..My 305 has been catless for about 5 or 6 years now I think....My TPI car is dual catless...lol.......Not an issue unless you have tough inspection laws, or just don't know how to get around it...I find the sound to be better, deeper maybe, I know some will argue that, but im only talking about my car....Have never used Hookers headers on a third gen, had them on my Dodge Bracket car, and loved them..I have eddys on my 305, and Hedmans on my 350..The headmans seem more manly to me, seem to be built a bit better..Performance wise I doubt in stock, or near stock you could tell much difference between the 2....Just my 2 cents worth..Good luck.....One more thing I will say is if the motor is in good tune, the emissions are not going to be much different with, or without a cat...The Cat police have never nosed around here, not saying they couldn't, but it is unlikely you would ever get noticed by a fed..Unless of course you post on internet boards....hahahaha

UnderCover89TBI

iTrader: (25)

I would never remove my cat!

crytical point

I bought it that way

UnderCover89TBI

iTrader: (25)

I bet you did