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Debating about adding high flow cat

2914 Views 22 Replies 7 Participants Last post by  RemixPinoY
I have a 95 SE, currently only performance mod so far is a Apexi n1 exhaust. I have a chance now to buy a high flow cat and am wondering if this would be a + or - for me. Would this help in power gain for my car? Also is this legal to do in CA? I know it's basically all for looks but would this be illegal to do?
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Well I am not sure about CA but I put a high performance catgo cat in my car and it does BETTER than stock and flows better too
What did you notice? Better top end? Faster acceleration?

What exhaust was this on? And after you did it, how much louder did it get?
obviously it wont be as restirctive as the stock cat, but you wont see unbelieavable gains....... too bad your in CA.... i dont have any cats at all
Haha yeah I know I know CA sucks for cars but life here is nice as long as you got money. So is 130-150 bucks for this piece of metal worth it? Will I get a small bump in power? 3hp, less restriction and slight power curve improvement?
130? i got mine for 20 off ebay and its a real catgo cat....came with warrenty and shit
lol I don't have an ebay account =[
$130 for a catback?? wow lol I bought my HKS hi power exhaust for $520 =S I love it though. But ya know, if your aiming towards NA performance, You need to go with a smaller piping size. Too big and you'll only be losing back pressure: Bigger piping for Turbo. May seem like performance yea because your STOCK catback is heavy so you throw on a much lighter catback and there's some weight loss. And If I remember right, when I was looking into buying my catback, the Apex N1 exhaust piping was too large for NA. The reason why I bought the HKS Hi power was because it benefited NA and turbo...mainly turbo. But the piping is only about 72mm I think so I went with that. Bad ass exhaust though =D Im tellin you.
And by the way...CA does suck lol. My supra is ALL stock except the catback. I got pulled over and asked to open my hood. Cop accused me of having a lowered car, modified cams lol, AND ILLEGAL BRAKE LIGHTS.....that one pissed me off lol cuz i have STOCK Toyota Supra tail lights. Thats when I was convinced he pulled me over just to check out my car. He let me go with a warning lol.
N1 is too big? I thought it was like a 75mm exhaust? Mines not 4 inch it's a 3 but slightly bigger I believe like 3+. And no 130 just for a high flow catalytic converter not the exhaust. And yeah I just signed up on ebay, can anyone link me by pm to what they believe is worth getting? I have no experience using ebay so tips are welcomed please.

Also I'm not looking for NA performance mainly but if it helps as I am now cool, I'm looking into eventually swapping motors so building up my exhaust is a now or never thing. So if I stick a high cat with my exhaust will I really lose back pressure? And how much weight would I be saving roughly estimating?

So with my current Apex N1 and a possible high flow cat would it benefit me or will my NA be losing power? I'm also getting intake for free from a buddy so will all three help me or am I just losing out in power?

and I love my toyota that sucks, and wtf is it illegal to have a lowered car? I can imagine because brakes cannot be seen but wtf Supra's are already low, and if you ever did mod your engine would you keep it stock looking? Would a cop be able to identify parts even if it looked stock? And thats funny if he just wanted to check your car out. Was he being an asshole about it?
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$130 for a catback??......
lol no he means just the cat.....nothing else.....
So anymore opinions? I'm still waiting for the guys response, but would like more feedback from others as well.

BTW Twinturbosura94, I'm still new with Supra's but your trying to run 900hp with a t61? Thats incredible man.
Oh lol just the cat. I was gonna say I got ripped! So the N1 is 75mm? I didn't know that. I thought it was larger like 90 to 95mm. Thats not too bad even if you were to put a turbo, it would be great. Honestly, I gained a good amount of power, but If you want full potential, you need to add more mods to ur car for ur exhaust to take full effect, ya know? I'd say I gained a good what...maybe 15 or 20 pounds. Stock exhaust compared to my HKS is a big difference and it helped. Felt like my Supra was quicker. Its noticeable. But yea my opinion...get the exhaust. The N1 has a good sound to it too, although i prefer my HKS sound. And yea that cop was a dick lol. He was cool and everything but just wasted my time. He didn't say lowering ur car is illegal but he did say any mod to ur car is illegal which I thought was complete bull. He either has NEVER seen a Supra or he loved it lol. And he wouldn't know if I had new cam shafts lol. Just a cold air intake which I don't have. Most cops around here are pretty cool though. But anyways, catback and'll be getting power. Even with just the exhaust. I think it's worth it
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Alright cool! Yeah the Apex N1 ( I keep thinking Apexi) is a 3inch exhaust as advertised for what I have. But it's slightly larger than that I know for sure, it's close to a 4 but not quite. And yeah so after I add a high flow cat, I will be getting an intake for sure. Afterwards that will be it for my car in terms of performance. I want to go turbo or swap engines so I don't want to waste more money on parts I may potentially just not use at all. Everything else will be going into exterior, interior, sound, and suspension and wheels.

Anything thanks for the help guys I'll be getting this then for sure. So 130 sounds right? And since I am a noob, course I'm only 17 how would this cat be mounted? By welding or can it clip on?
1) I noticed some backpressure from the hi-flow cat

2) Damn search function....but i read a thread somewhere in the MKIV sub-forum about a person who had 730rwhp and lost 30rwhp after installing the hi-flow cat and was tuning with an aem ems

3) here's a thread about jdm hi-flow cats

4) Not sure if this is still true in California, but a long time ago, they were pulling over lowered cars defined with license plates being below the 18" height. Probably not used anymore though as a lot of sports cars these days look/are lowered from the factory. I guess I worry more about scraping speedbumps, curbs, and hills

5) Sure, people have their "methods" but it's technically Only legal if it's CARB approved (i'm 90% sure of that...i think? heh).

6) regardless, if they want to, they can get you for anything. They don't even have to care if you have a cat or not. Even if it's a stock car, they can point to and question any part. They can simply send you to a ref if there's any doubt or reason -- legit or not. This has been done. In fact, I'm sure there are tons of other stories out there as well.

7) weld

8) Conclusion is that the hi-flow cat doesn't restrict too much. It will not appease cops but may help in general especially if CARB certified. It helps with making the car Not sound like a straight-piped / race-prepped / ....

9) i highly recommend going 2jzgte swap over na-t unless there are huge advantages to your 'methods' that counteract the fact that you're in california heh It is not uncommon that it only takes one cop in a bad mood..

10) yep, cali sucks for this unless $$$. Maybe it's true for the entire nation that 350-400hp+ cars are being pumped out And advertised that way to anyone with $$$ but they are seen flooring it around and weaving way more (from my experiences) while they pull over stereotyped import cars for stupid sht
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Thanks man very informative explantions.


1) Backpressure is good or bad? Or is it too much is bad, a little is good?

2) Is it likely I will lose power? I've had numerous people tell me it's good if I get one but just want to make sure.

3) I'll read up, thanks

4) I do not plan to lower my car much, my car currently sags at the rear and the front is high due to worn out suspension, so I'm switiching my 114k mile suspension to stock TT suspension with about 45,000 miles, got it from an old forum member who no longer his Supra and was here about 5 years ago.

5) I'll have to ask the guy I got suspension from if it's carb legal although I doubt it. If not where can I get a carb legal one? And are there any carb legal performance parts for the Supra at all? And yeah I know the methods but it's a pain to find someone who will help me in my methods. If you know PM me please thedarcsage.

6) And yeah I'm worried about that, but since I already bought my car modded a bit I'll just BS if I can't find a way to remove my exhaust and other pieces.

7) Alright, how much does that usually cost?

8) I def. don't want to sound like a full straight pipe, my cousin has a 240sx with a home built exhaust and it's straight pipe. Stupid thing spurts out flames and is way way way too loud. So adding this will be a bit louder but will it be a lot louder than my current totally stock car with just n1 exhaust? Will it be rumbling loud?

9) And with the 2jz swap would I be okay going with aristo? And seeing as how you and I are in cali is it legal for me to swap with a Japanese motor? If I were to convert all the things like sensors and ecu could I somehow register it? Or is it possible to get it bar exempt all together? You know I really wish Cali would offer an option of us paying like 2k in fee's just to run a modded car and without having to worry about parts and etc.

10) I don't fully understand, do you mean there a lot of new 350-400+ HP cars running around doing more dumb crap than imports that look fast that get pulled over for being an import?

I have so many questions if anyone would like to help me out in planning out my car please IM me or PM me.

My aim is: lil pinoy bopper

Thanks all for the help so far!
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Hmm, I dunno much else about hi-flow cats other than
for me, a hi-flow cat made it quieter ... no idea how it compares with other noise levels, but it depends on how it's driven i guess

welding usually isn't expensive $15-30 or less depending on connections

quite a few people at the meets have done the swaps er...engine replacements, so they could be helpful with the legal details and the exact process/steps/plan-of-action...don't take my word for it, but i think if my memory is correct, it should be legal once u have the usdm parts and pass it with the ref...(??)

yeah, more dumb crap coming from daily drivers, and let's not forget ricers... i guess it depends on the driver
Thanks thedarcsage you've been great help. So it made you quieter thats suprisngly different. Oh well I really don't care if I get a little quieter or a little louder. As long as I'm not silent, or an alarm clock I'm cool.

Okay cool welding isn't expensive I'll have it done quick then.

And which meets do you know the peoples names I could PM?

And yeah I've seen stupid ricers pulling stupid lane changes in high ways, stuff I'll never do. I mean you know honestly if I ever killed someone or hurt someone and went to court for it, whats my excuse to the Judge? I'm sorry I didn't mean to kill? Yeah right I knowingly sped and knew what could happen. I'm not the type to do stupid shit like that, and yes I know I'm only 17 and yes I know most believe I would but in my own character of thought I will never do that. I cannot live with myself if I ever hurt anyone doing something especially driving like that. So no worries I'll never be added to the statistic haha.
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