Would there be a real difference in HP with either deleting the cat or completely gutting the cat?? I have heard that with either way you go, you will get alot of HP, so I wonder if anyone knows what kinda of gain I would get???

 

Not sure how much power gain is there, but it makes the car unbelievably loud. Blown 4-Banger had a delete pipe made for his custom 2.5" exhaust with a magnaflow and I could hear his exhaust for over a 1/4 mile away, and that was with houses and buildings between me and his car!

 

you'll lose alot of bottom end but gain a few ponies up top.......

i would just buy a high flow cat and call it a day until you go into big boost...

the only benefit i see is if your getting 1 or 2 degrees knock, you remove the cat and it may go away
but yourll be targeted by cops and ricers for being soooooo loud..

or just get the CTI header and down pipe w/ removable I pipe you can take the cat out on the track and put it back in on regular DD days

 

Would a bigger resonator help with the noise? or is defeating the purpose??

 

Cats these days flow 99% of that of a straight pipe. Basicly its not worth ripping them ot anymore.

 

is the high flow CAT worth the money?

 

Eh, I took a prybar and just gutted the cat. Definitely helped with nay knock. Also, I didn't notice any bottom-end loss but the car did get somewhat louder.

 

We'll find out in a week or so when Blown 4-Banger gets his new exhaust on. He is gonna get a custom mandrel bent 3" with a resonator and Magnaflow.

 

Sorry, I don't agree. I would say there's a good 10whp going to a straight pipe. The stock cats are restrictive, and on top of that, they get too hot and fail alot because they can't keep up with increased boost. I've personally looked at our stock cat, and you can't even see through to the other side! Putting a straight pipe in decreases kr and boost, and I've seen nothing but benefits from mine. Also, unless I see proof, I'm calling BS on the loss of low end torque as well. With that said, you're exhaust will become alot louder, and sound more raspy, so choose you cat-back wisely. I happen to think that the Corsa Touring sounds great with no cat!

 

yes there is restriction on the stock piping the hold back air flow replacing that would make you car run alot better

the restriction is around the 02 sensors

 

I removed the cat and there is a difference in power. It got about 3X as loud so if you don't mind the noise...

 

Mine got louder but not 3x as loud. Did you do exhaust too?

 

Have the SCDyne header, still on the stock resonator and piping with a Magnaflow muffler and tip. Has a ripping sound. Idle is a bit louder but at WOT is where it got 3X as loud.

 

This is my next decision to make,, and probably the hardest yet.

I've gone back and forth sooo many damn times about which header/DP to get

I have a question on the CTI product. It comes with that removable I pipe, but they also sell a separate dowpipe. This may be a dumb Q, but does the I-pipe go all the way to the catback? So all you would need is the CTI header, and a cat back? I was just curious because on their downpipe desc. it said that it went well with their header and cat back

So does the downtube replace the I-pipe?? Or am I being retarded?

 

Shorty headers won't connect to the catback. It needs the downpipe or if stock it needs the downpipe/ catalytic convertor. Edit,,also a flexpipe connected to the downpipe.

The downpipe sits between the header and catback.

 

I lost all my backpressure and lost like all my low end tq...my car is a dog...and its so loud my ears bleed if I stand next to the tip with my ear to it when someone revs it

 

I understand that. But when you buy the CTI race header you get their shorty header, AND the I-pipe,,, I just didn't know if the I pipe went all the way back to the cat or not

 

Ahhhh now I see what you were getting at. Don't mind me I just finished work.

 

^^No worries. I take it you don't have an answer for me than

 

OK guys, I read a great article on this in a performance catalog. The did a dyno test with a straight pipe, and magnaflows high flow cat. They only showed a 1-2 hp difference with the test pipe. Now you have to realize by not having a CAT you are breaking a federal law. So is it really worth the 1-2 hp?

 

the i pipe is a removable cat pretty much it doesnt go all the way to the catback just a few inches before and after the cat

 

^^^Thanks, so I would have to buy their downpipe as well if I wanted it to all bolt up to a cat back.

 

Really, what about when you dyno'd side by side with Rob, basically same mods, and he had more torque than you, you had a cat, and he didn't.

 

I made 1.5 more hp tho!

Btw...that post oozed sarcasm...who really sticks their head next to the muffler and has someone else rev it and we all know backpressure is bad mmmkay

 

I'm just messin with you, no "oozing sarcasm". But in all honesty, there's no proof that you actually lose torque by getting rid of the cat. If I had the money, I would dyno the car with a cat, and then without to prove it's worth more than 1-2 horsepower. Also, Dan, if I recall, you were only trapping 103ish when you raced with Rob, and were getting KR. Funny how when you finally took the cat off, you trapped closer to 109 and didn't have kr?