my car, 95EG with a 97GSR obd1 swap..with the following mods:
p72 square box(stock)
intake
Skunk2 Intake Manifold
Soon to have TB bore out to 64mm to match up with Skunk2 IM..by Maxbore
Hondata IM gasket
CTR cams, intake and exhaust

stock header, cat, exhaust..

want to know what would be better?
2.25" header, cat, and exhaust or
2.5" header, cat, and exhaust

no plan for future..maybe hondata s300 with a tune..maybe..but for now it's my DD..
just let me know whether:
A) 2.25in
or
B) 2.5in

i'll do the rest..oh yeah, i don't care for high flow cat..want to keep it quiet but a tad louder then stock..so i'm gonna get magnaflow universal cat..

thanks

 

Quick question...why not get a high flow cat?, That's just adding to the restriction, and honestly after I installed mine I didn't notice any change in tone or volume (or smell). It seems like an obvious choice if you're serious about making power.

 

^^which brand of HF cat did u get? magnaflow? i have the universal apexi muffler sitting here..ppl said they are pretty quiet..i want to keep it quiet really..

 

Its always best to keep everything the same diameter! your stock header is 2.25!, if you get a 2.5 cat to a 2.25 or even 2.5 b pipe/catback your gonna get a uneven flow either way and it will result in power loss.
Your plans for the future with those mods and especially the main ones in your set up imo dont make sence no offence, i dont know why you are running a stock intake and header on your setup? your killing it man! check this ive always made great n.a power from the b series take my advise and you will thank me,
first off with your setup the 4-1 jdm itr header will be more than enough up to 210hp,and its other advantage is the real oem header is still carb leagal in some cases and the replicas can have the heat shield on to look oem! (its what i still have!) so with that header it has a 2.5 " collector so make sure the cats inlet on outlet is 2.5'' some aftermarket ones arent tru 2.5'' on both sides, or like me have a piece of 2.5'' pipping added instead, make sure your catback is also 2.5'' i like the buddyclub spec 3! anyways get a aem ITR 3" cai its carb leagal, i got a mint one for $60 used before, if you want to be stealth re order a carb sticker for your year its like $10 shipped, so it looks like the correct intake for the motor/car, this is dyno proven to make the most hp n.a ask church automotive if you dont believe me then, since you got the sk2 manifold get the most out of it! since your porting the tb port it to 68mm not 64, 68mm is the best size unless you have a full out race motor like ported head/higher comp.,itbs ect..then 70mm+ would be best, just get a 68mm tb there not to expensive used and get a 68mm thermal tb gasket along with porting the manifold to 68mm as well. theres absolutly no reason to go with the s300 the hondata s100 is all you need unless you plan to go turbo sometime later then thats when you need the s300 so dont bother spending all that money i always recomend the hondata s100! retuning with this setup i bet you will hit 190- 200whp gl. sorry for the long mess. lol.

 

^^thanks for the advice..i don't have to worry about CARB where i live..no such thing here..as far as setup goes, i thought the stock piping sizing is 2" or 1.8"..got that info from team-integra .net..another thing too, i also THOUGHT the skunk2 IM tb port is 64mm..well i contacted Maxbore and he told me that..so i don't know..i never thought of hondata s100, could be a lot cheaper too..200whp is my goal..i don't need any more then that really..getting my hands on the 4-1 JDM ITR header would be hard..i've look in the past but hard to find..
i saw the aem cai that is a hybrid..meaning if u got a b series on an eg chassis, this is the intake for it..

thanks for the info..i'll keep looking i guess..

 

The sk2 i.m might be 64mm but since your gonna port the tb just have them port match the manifold to a 68mm tb! if you dont have to worrie about carb then forget about a cat or high flow test pipe crap its just a waist of money imo, get a 2.5'' pipe fitted! at a muffler shop cost me like $30 at midas, just get the jdm 4-1 itr replica header on ebay! its like $150 -$200! and it makes good power, they claim 10hp more than the oem piece, i still have mine on my high comp. jrsc'd gsr! just make sure the aem cai is a 3", thats the important part only the aem ITR cai came 3'' this will make the most power especially since you have cams and that intake manifold. the hybrid intakes might be 3'' not sure though.

 

i'm having the oem TB ported..the max they can go is 64mm..same as the skunk2 IM inlet..so i'm just gonna stick with that..the hybrid intake is 3in, i checked it...i'm trying to stay quiet..so if no cat but straight pipe, then i'm gonna have to add a long 18" resonator to keep the sound down..if i'm by myself then i don't care about the sound but my gf is with me most of the time..and i just hate the noise when there are other ppl in the car also..plus, i want that stealth look and sound..it's a sedan and noone would expect there is a b18 in it..

 

My exhaust sounds almost stock unless driven hard, before the magna flow muffler i had the oem gsr muffler and it sounded completly stock but with the magna flow it sounds more agressive but still is quiet for what it is.. thats until driving full throtle, it sounds impressive! imo, i lost hp with the oem muffler because it btlle necked from 2.25'' to the 2.5'' bc spec3 cat back, once the magna flow muffler was added it was free 2.5'' all the way through and sounds and performs great.
https://honda-tech.com/forums/appearance-build-threads-122/c-street-sleeper-want-feedback-comments-lots-pics-%2A%2A%2A-2556604/

 

2.25 would b the best way to go uneven flow means a loss of power keep everything the same diamiter

 

damn..clean car man