hi guys, wanted to ask a quick question. I am thinking of upgrading my standard subaru exhaust manifold to a (4 into 1) stainless steel tubular manifold. on most of the websites that sell these products they say you can can expect gains of about 25bhp depending on supporting mods. i wanted to know how true is this?

and lots of people say when advertising, this is not some cheap ebay crap... what do they mean by this? because looking at whats available on ebay and comparing them to other websites, they all look pretty much the same! i was hoping somebody could shed some light on this.

the headers i had in mind are advertised at this site:

Subaru Impreza Stainless Steel Tubular Manifold Spec2 --- Japspeed Performance Parts

 

From what ive read and been informed from various tuners/mappers, its not really worth it until you get over 380bhp.

looking at your scoob spec i dont think it would be worth it on a vf35. Harvey ported headers are very highly recomended on here and Harvey is happy to help also.

headers wont add 25bhp but you will prob see a gain from them. but they do add torque.

i was running ported headers on my 18g and made 361/322. i recently put rogerclark tubulars on and i can feel the difference in mid/top tq. bottom end went 4 days after fitting so havent had them mapped in or on rollers to see the difference yet.

also i have 2 mates running the cheap ebay jobs on cars. one is running 550bhp other 400 and no issues. they are worth a try imo

hth

 

you wont notice a big difference in performance til a remap but it'll change the exhaust note bit deeper with un-equal length i noticed and you'll lose subaru burble if you stick on equal length

i have un-equal length ebay headers and no issues and im running 1.4 bar about 20 psi

and if you do get a set heat wrap them and use good gaskets dont use cheap ones that are like cardboard

buy some gaskets from tsl or similar

 

Headers can give a useful increase in power over a wide range, usually at the expensive of slightly later spoolup. I've seen gains of 25hp i the midrange despite an increase in peak power of only 15hp or so, this on a car with around 365hp before.

 

you guys have been very helpful. i just like to hear from people that have a personal experience. it helps in the deciding process..

p.s i have a zero sports hybrid that is AR/20 roller bearing turbo thats going on now. Its capable of holding 25psi or 1.7 bar of boost i am told. i also have a set of 550cc injectors going on. i'm hoping (after a remap) of figures in the region of 380 to 400bhp. i am told that this maybe possible.

i just thought that uprated headers may help me obtain my target bhp band.
cheers...

 

Id be interested in seeing how the turbo gets on after. spool time etc.

Harvey advertises on here. top right of the page his ads pop up from time to time.
give him an email with your spec and what you want to achieve. Harvey has to be the most helpfull person on SN without pressure to buy. sent him loads of emails and always get a reply

 

I choose headers with a 3-bolt joint between the manifold and the up-pipe. I seem to think they are less likely to leak, IIRC

HTH

dunx

 

Depends on your preference. Later spool is very manageable on a type R gearbox for instance, when combined with 8000rpm rev limit. But a UK car with wide spaced gears and 7k limit, a 3000rpm useable power band might be not too much fun.