ok so my question is still not yet answered, how can a 63mm testpipe be better than a 70mm testpipe when using a 70mm exhaust

 

the other thing you have to look @ is how does it bolt up. You can't go 60 --> 70(TP) --> 60(factory exhaust) If you buy a 70 tp, you need the 70 exhuast right away. I have a T1R 60mm TP, and 60mm Exhaust, and its does GREAT. Unless you are highly NA tuned, Want something stupid loud, or F/I 70mm is not needed. for a good 220-230HP N/A S a 60mm exhaust is Fine.....

 

it isnt, it will create a bottleneck effect in your exhaust. You want your piping sizes to match wherever possible.

-Ian

 

If you bolt on a 63mm testpipe with a 70mm exhaust, then your whole exhaust system will not perform at its max as the other member mentioned "bottle neck effect".

 

if u plan on getting a 70mm exhaust than get a 70mm tp , t1r or invidia are availible , on 06+ s2k the defouler that the berks comes with for the cel doesnt work . i have 2 defoulers on my t1r and got a cel , hurd others try steel wool and still cel. believe theres a fix where u install a resistor in the o2 wiring but not sure how thats done so im waitin on my bro smirf to do it to his since he's done it before

 

well i have already ordered the invidia n1 single tip 70mm exhuast so i definately wanna go with the 70mm testpipe, and i plan on going to boost but not until the car is paid off. i am just worried about having a cel. people with the quality TP's that arent supposed to throw codes are throwing them. i just need to find out the hands down best way of keeping a cel from happening when running a testpipe

 

Well one thing that is not noted on your post is when Honda updated to the new ECU for 06+ it got alot more sensitive sensors. So you guys with +06 Cars its either hit or miss. Sucks but there is not much you can do..........

 

both my buddies have my 06s i have done the mechanical simulator and it works...NOW when we go to the track after a day of heavy driving in vtec it will throw the CEL. No matter anyways as this does no adjustments to fuel or timing. just an eye sore

 

The 63mm test pipe is all you should need, FI or otherwise. I'm pretty sure there are no headers out there with a 70mm collector outlet on them anyway...

Either way, Berk determined that the 63mm pipe would net the highest exhaust gas velocity for the widest range of vehicles and their research shows in the numbers.

 

i have a 06 s, and all you need is two o2 foulers, one should come with it, i have a berk and i had to buy another o2 fouler.