basically my cat broke a while ago... it was a very old cat form the previous owner and what happened was the 2nd filter in the cat broke and turned 90 degrees and partially melted into the exhaust covering 90% of the piping, thus explaing the rattling and major power loss...

anyhow the old hi-flow cat was a 2 1/2" that was welded onto my mugen twin loop cat-back, and since i had to change my cat i decided to replace the bottle neck before the resonator with new piping of 60.5mm

problem is they gave me a 2 1/4"(ID) hi-flow magnaflow (carsound oz version) cat...

my question is am i back to square 1? what i mean is basically it's still bottled neck to some degree as like before? or is there such a small difference between the 2 cat size's that it won't matter much?

my itr is stock except for the mugen twin loop, later installing the mugen airbox and maybe a yr or so down the road toda header...

so plz tell me what you guys think plz... all comments are greatly appriciated! thx

 

any thoughts from anyone?

 

what kind of exhaust parts do you have before the cat?

 

I've wondered about similar things... Does your exhaust system only flow as good as the smallest diameter?

 

bottlenecks? that is the definition of a bottleneck.

 

Get a new setup. New piping with an SMSP cat so you get rid of the bottle necks and its 2.5" all the way through. That will take care of your problem and give you the best results. Im still a little confused as to what you're saying but if you're running a 2.5" piping already, just make sure that the cat is the same size so you flow at the same rate. Bottle necks in the B pipe is one thing but having the same " bottle neck" on the cat is another, it also makes the cat less efficient.

 

thx for the replies guys

just let me clarify plz,
i originally had a 2 1/2" high flow cat with mugen twin loop cat back exhaust, and we all know that the mugen has a bottleneck just before the resonator right?

so while i was fixing my cat, i decided to fix the bottle neck system by replacing the piping before the resonator with a new 60.5mm ID piping.

my question was, if infact that i changed the piping, but due to the new 2 1/4" cat would there have been a power difference at all?

it feels as if throttle resopnse is down a bit, but this could be due to the fact that original the cat was slightly broken, therefore a bit of better highflow without me knowing, and since it fixed now that things are back to have they are meant to be...?

i know that throttle resopnse is down because i have a VAFC2 installed but untuned at the moment and i use the throttle meter to read my readings.
before my cat broke i open the throttle to 20% for me to get to a certain speed and power range, but now days it takes up about 30%, even 40% sometimes to be able to get the same result. i understand that this is only based on feeling and tempreture is variable,but i was interested to find that if i did the wrong thing.

i will be changing to a 2 1/2" cat much later but just curious to see what your opinions were in regards to power loss etc... keeping in mind that the mugen twinloop is supposely 60.5mm = 2.38" not 100% sure if that's ID or OD, but i know for sure it has about a 2-3mm thick wall, while my cat is has an ID of 2 1/4" =2.25mm

thx again for the input

 

oh yeah,
before the cat is stock extractors, but in a year or so i will be investing in toda headers, the collector is of 60mm ID if im not correct this will be able to be bolted straight onto my current setup right? please note there is an oxygen sensor in the same place of the toda header.

 

240 views? no one has any other further opinions?

sorry if i totally do not make sense...

but just trying to figure out if i've actuallly managed to power down from such a small but significant change