hi,im thinking of fitting the oe sti backbox on my v4 sti type r to quieten it down.currently running a h&s sports cat downpipe with h&s straight through centre and ninja backbox.
its making 338/316....
will it be too restrictive?will the mapping need altering? or is it a case of fitting it back on and all will be well but with less noise?
thanks

 

It will flow less air than the H&S backbox, the standard one does a full 'S' in the backbox where as the H&S is virtually straight through with a baffle, it would require a slight remap to be 100%

Although I doubt that fitting it would do much harm being slightly restrictive would probably lend itself to slightly rich running, someone can correct me if im wrong, it will defiantly quieten things down, I used to a run A straight through system de-cat with just a H&S backbox on my old v4 sti wagon, that was loud.. the standard one is MUCH quieter, still have the standard in the shed I think.

 

thanks,i dont mind if i lose a minimal amount of spool/power as i personally dont think it would be noticeable,im just trying to make sure it wont do any harm without having the map tweeked????.i know it will drastically reduce noise levels,so just fancy a change for a while,without the noise.if it will make it run a little richer then thats fine isnt it?

 

got a oe sti v7 sti wagon backbox if you need one mate nice and stelthy

 

ive already got an oe backbox,just wondering wether it will be ok fitting it back on the car after mods and remap etc as its already mapped for 338/316.

 

anyone?

 

anyone know if this is ok to do?

 

 

No it's not ok best scenario ...do it and your turbo will get '******* hot' you will feel it aswell and drive nasty Worst scenario you get muchous det spikes and you do some damage. I am running 1.4 on my wagon and it hated having the standard box on, it has awful flow and a very pinched exit pipe !

 

ok mate,thanks,thats all i need to know.

 

I'd just ask your mapper in fairness, or any mapper for that.

 

i would have thought this would be an issue at 400+ bhp,but at the 338 is it really that restrictive?

 

fpmsl !

 

 

Sounds like you want me to tell you what you want to hear mate is all. No it will not be ok if you are running anywhere near enough boost to allow you to hit 338/316. At the risk of repeating my self (as I wasn't telling porkies, guessing or speaking about something I haven't tried)...best scenario ...do it and your turbo will get '******* hot'... worst scenario you get muchous det spikes and you will do some damage.

If you have or have access to an original STi BB, measure the OD of the pipe that exits the box, it's very very small ! on the NewAge STi BB its considerably bigger which is why I run 335/375 on one in my Spec D.

OEM STi BB is not suitable for your car at that level of power/boost given it's been mapped for more flow. The back pressure will not be your friend

Or I could be lying and it's fine until you get to the magic 400+

It's a bit like asking enough people whether your gearbox will take 350 running your mods. Someone will say "yeah fine mate" at some point IMHO No.

 

Not just me that thought this?

Another member who was 'careful' about running well into the 300s has just stripped 1st gear

Anywho, to the OP, it's your car so do as you wish but ignore the above advice at your peril..

 

lol,so a newage sti backbox would be ok at this level?i thought they were basically the same?
so, at what level will my gearbox break?

 

Nope the Classic box is far more restrictive You could well use a newage one if you mod or fore go the middle hanger.

 

ok thanks,is there any other options for a quiet backbox?
what about prodrive? any others?

 

Revolution cat back, inward rolled tip, fit, forget, move along now.

 

i only want to change the backbox,as i dont want to have to tweek the map,which is quieter?newage sti box or prodrive? and i assume i wont be needing a map tweek if i chose either of them?
thanks so far 53

 

99gw, I have a Prodrive bb sitting here doing nowt (I also have a 2.5" straight through s.s. centre as well).

The only thing wrong with the bb is the mating flange is shagged - its seating face rusted up a bit and therefore wouldn't seat very well with the centre section's flange. So you'd need to angle grind the flange off and weld on a fresh one - no biggie.

There are no drillled holes for sparkplugs neither

 

lol.
would it not mate up ok with a fresh gasket and plenty of sealant?or is it proper fooked?is it for a classic or newage?

 

what will it cost me for the prodrive back box you have if it still for sale ?

 

For a Classic - it was on my STi 5 with that centre section before I got it remapped.

API advised me about the flange issue prior to fitting, but I went ahead and had it fitted anyway. There were no noticable gas leaks for the time that it was on. But don't know whether it would have eventually blowed, as didn't have it on for long (because I got a true 3" turbo-back system for my remap later on).

 

hang on a minute pal!

 

craigo, I bought it off a member on here for £125... But he sneakily didn't tell me about that flange issue.

So what about £75 + courier costs?


However, it's only fair that 99gw has 1st dibs.

 

go on mate, its yours if you want it...........

craig

 

ooo,too pricey for me joz,carry on craigo!

 

sneeky ****** !!!