its illegal to have an aftermarker exhaust. did it stop 95% of the people on this board? pretty much any performance mod you do creates more pollution. the more power you make the more fuel you burn which in turn is the more exhaust gases released. so should eveyone stop modding their cars? from Honda making the Accord go from 200hp to 240hp it created more pollution

and its useless on an NA 4 banger. with a turbo its night and day with and without a cat

 

The poster made no mention of a turbo, and in that case there are high flow cats as well.

Also at least here in NYC aftermarket exhausts are NOT illegal, and there is no code to have your car confiscated for removing your muffler. All you'd get is a ticket for the noise. Remove your cat on the other hand, and you could lose your car.

Also who said a high flow cat or no cat always gives more power??? Ive been on this board a looooong time and seen a ton of info on it. On a NA 4 banger Accord, dropping the cat for a straight pipe, or using a highflow cat will give negligible, no gains or even a loss in power. For the money, time and effort, its a pointless mod even with Headers, Intake and Exhaust.

Ive seen dyno's on 4 cylinders putting out more power than the Accord which LOST HP with a highflow cat, and more with a staright pipe. SCC did a test within the last 2 years which showed the same.

Even on turbo cars, unless you really pump up the boost, swap out for larger turbos, or drop a turbo in a NA car whose exhaust would then be too restrictive, you really shouldnt get much gains from a straight pipe vs a highflow cat or regular cat. The much longer crush bent exhaust is the real bottle neck.

 

i would just leave your cat alone, like elite accord said its bad for your health, the cat contains carcinogens (cancer causing agents for those who don't know). just leave it man its really not worth the little power gain, i would understand if you were runnin like 15 psi of boost out of a turbo you might get about a 5-10 hp gain, but thats about it.

 

i've seen a turboed Prelude go from 210 to 260hp by removing the cat and replacing it with a straight pipe. it was right on the dyno. did a run of 210. un-strapped the car. replaced the cat. strapped it back down put out 260 something on the next run. i would spend $40 for 50hp. i agree with you that it wont make any power on an NA 4cyl. you'll lose a lot of low end power. but it does nothing but help on a turboed car. i've also seen a turboed civic go from 145 to 170 with putting on a straight pipe and pulleys. now that was like 3 weeks apart from the 145 to 170 but no other mods except the straight pipe and pulleys which would gain like 2hp. the cat makes a huge difference on a turboed car. but to answer the mans question. no you dont need a high flow cat unless you go with forced induction

 

pullys will do like 10-15

 

My friend just did it to his oldass n/a prelude and it hauls top end better than before, but he does lose on low end and supposedly it smells funny...-er...than before. my other friend drives an n/a rx7 and it helped his top end a lot more than previous too. from personal observation, it DOES work so unless you have dyno results to prove that it doesn't work or you've done it yourself to say it's a waste of money, then with all respect, stfu.

on the other side, it's a federal offense to be driving without a cat. $2,500 fine. you're gonna kill or endanger us all and give us cancer, you'll be laughed at for paying an unreasonable amount of money for your mod, and you won't pass smog...with the exception of the last thing, it's just like street racing.

does anybody know how often you have to get your car smogged? mine is a 2000 and i don't want to overshoot the date and not get my car reregistered when i should.

 

...that's not cool. its turning '03 and i haven't even thought about smogging it. hahaha.

 

Well my personal experiences are no different than yours, friends did this and that, except my friends noticed the opposite, plus like I already stated, I have been here for well over 7 years now, and ..............news flash!!!!!!!!!!, this is not the first time that people have tried dumping their cats. No one showed any real gains.

Also like I also already stated, SCC did tests and showed a real dyno, not a butt dyno of the last Nissan 240 that showed a loss in power with a highflow cat, so unless you have more than all that, why dont you respectfully STFU newbie. :naughty:

 

here's the results...
http://www.rx7club.com/forum/showthr...at+remove+dyno

not bad eh? but yes, there is a lot of low end power lost i guess. but 13-15 hp proven gain isn't bad. for changing/removing the cat and the airbox between runs.

 

just don't do it.... it's more trouble than it's worth