I understand ITR's come stock with 2.5" piping, then why are most to all aftermarket companies that make cat-backs for ITR's make them in 2.5" piping. Wouldn't you be better off just buying an axle-back instead of a cat-back since the piping is the same size anyway? You would also be saving money. I'm running an Apex RS Series cat-back on my car, and it seems like there's no difference compared to stock. It sounds a little deeper but that's about it. It feels as though 2.5" is not big enough for an ITR. Seems like we need atleast 2 3/4" or 3" piping. What do you guys think, what are your opinions, what are your comments, etc?

 

I thought it was 2.25.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ninjaboi_on_X &raquo;</TD></TR><TR><TD CLASS="quote">I thought it was 2.25. </TD></TR></TABLE>

It is 2 1/4" with multiple bottlenecks but relatively free flowing as compared to many other stock and aftermarket catbacks.

 

ic, they're 2 1/4, but 2.5 still seems a little too small. Like i said, the rs series didn't really make a difference.

 

maybe that muffler is too restricted for the car... what cat-back are u guys on, and was there a difference? i'm thinking of getting an hks hiper axle-back since i'm getting a deal on one. u guys suggest doing that?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hyper16-Johnny &raquo;</TD></TR><TR><TD CLASS="quote">ic, they're 2 1/4, but 2.5 still seems a little too small. Like i said, the rs series didn't really make a difference.</TD></TR></TABLE>

thats because you're not supposed to get performance gains from an exhaust.. for itr with mild bolt ons, you won't see much difference or any from switching exhaust systems..

once you have parts making more hp, then you might need a better flowing exhaust... say at 260whp i run 2.5" exhaust.. i'm pretty sure i would loose hp with stock exhaust..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hyper16-Johnny &raquo;</TD></TR><TR><TD CLASS="quote">u guys suggest doing that?</TD></TR></TABLE>

What I'd really suggest (in the nicest way possible) is to SEARCH a whole bunch since this topic has been covered more times that I care to remember. As for the stock exhaust, it is fine for stock to mild setup's. First thing to get would be a well designed Header and a High Flow cat.

There are more than a few well designed catbacks that will provide decent to good to very good gains for the R the latter to depend mostly on setup and tuning.

Take a long look at all of the older posts here about this topic, there's loads of great information out there, in short 3" is too big unless it is an extremely aggressive N/A or FI setup. 2 1/2" is said to be the best with 60mm being the very least you'd add on if you really felt you needed anything more than stock.


What is there an after Christmas rush for catbacks lately? There seems to be a load of previously answered questions popping up here lately, and I don't mean just grazed the top of previously answered, I mean beaten dead horse dragged through the mud previously answered.

 

i'm on pretty much every basic bolt on u can think of. aem cai, jg headers, apex cat-back, aem fpr, aem pulley, and a high-flow cat. i think that would be good enough for good flow. well, i wanted to get the hks hiper anyway. i'll just get that and see if there's a difference. there should be since its a straight flow muffler and the rs series isn't.

 

for what you got, stock exhaust will do just fine, anything other will add noise.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hyper16-Johnny &raquo;</TD></TR><TR><TD CLASS="quote">i'm on pretty much every basic bolt on u can think of. aem cai, jg headers, apex cat-back, aem fpr, aem pulley, and a high-flow cat. i think that would be good enough for good flow. well, i wanted to get the hks hiper anyway. i'll just get that and see if there's a difference. there should be since its a straight flow muffler and the rs series isn't. </TD></TR></TABLE>

Sounds like you had your mind up regardless of what anyone shared or what you might find if you searched around a bit.

I haven't heard anything about the JG headeR.

Best of luck though, And why not show us some dyno charts of your current progress? Then post some up after you install the new system to show the difference?

 

i'll try to get some new dyno sheets up...i dynoed my car with these mods already, but i dont think its was an accurate dyno. the reason why i'm saying this is because my friend had some internal work to his motor (11.5 comp pistons and thinner headgasket) and pretty much the same mods i have tuned, but i put out more hp than he did. i put out 165.9 and he put out 155.6. i'll post that dyno run of mine as soon as i can find it. my torque curve looks all retarted too. i should be atleast at 175-180 with my mods cuz i've seen other dyno sheets of other itr's and they put out like 178(on ave.) to the wheels with just i/h/e. I dynoed it at pomona raceway during the last nhra of the season in pomona. i did it at the quaker state booth. oh, and i ran a best of 14.7 on bald tires...

 

also, isn't a stock itr's dyno at 164? i can't be just making only 2hp more with my mods. there's no way that can be.

 

Numbers really depend on the dyno and the temperature.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hyper16-Johnny &raquo;</TD></TR><TR><TD CLASS="quote">also, isn't a stock itr's dyno at 164? i can't be just making only 2hp more with my mods. there's no way that can be.</TD></TR></TABLE>

There are different types of dynometers, some read high, some read low.

On a DynoJet, stock motors dyno anywhere from low 150's to low 170's depending on what type or ITR motor (11:1..etc) and/or how well it was taken care of. My car put down 170/119 stock on a dynojet, which is typically high for a USDM motor. On top of that, my exhaust setup netted me 16whp with just a JDM 4-1, T1R testpipe and 2.5" catback.

Your mods aren't exactly high power making mods. The AEM CAI does not perform well on stock ITR's, at least on the dyno. The only worthy Apexi exhaust is the N1, and that isn't exactly a high-power exhaust. The highflow cat is the only other mod you have that will likely gain you much power. Pully's dont do much, and fuel mods do nothing by themselves, you need tuning.

 

B2FiNiTY, u might be right about temp., it was in about 85-90% also the air was nasty. It was that one time when there were those bigass brush fires all aound s.cali. So there was a lot of smoke, ash, and who knows what in the air that day.