silverscoobydan

Hello all,

I am planning on fitting a used STi back box to my wrx (MY05) at the weekend. Is there anything I should know before I start??????

Cheers
Dan

Dave T-S

Yep, don't bother. The inlet pipe to a standard STi box is swaged down just before it goes into the box and it won't give you any advantage over a WRX one!

silverscoobydan

I wanted to get the STi on to beef up the noise rather than get any performance gains. The STI is louder/deeper than the standard wrx. I also prefer the look of the single exit rather than the twin.
Cheers
Dan

wrxseeker

iTrader: (1)

No it isnt any louder I'm afraid - The std sti box sounds the same, it just has single outlet

You need either a PPP back box (like I have on my MY05) with a round single exit or WR Sport box with an oval exit.

Both should be available on here or ebay 2nd hand if you search. Absolute Max £150 should be less.

chris_c201

Done the same recently on my bugeye....

Don't expect much of a difference in noise, its slightly deeper but nothing noticeable from inside the car...

As for looks it is defo much nicer.

For changing it i took about 45 mins, two bolts were pretty tight, get it up on ramps, soak bolts in WD 40 then i found putting a ring spanner on (13mm if i remember right) and hitting the other end with a hammer shocked them, once cracked the ratchet was fine....

There is three rubber bushes that hold them in, one at the front near the join and two ad the rear near the tailpipe, their pretty awkward to get off the metal rods that go into them, i ended up putting a small screwdriver through the whole and kinda levering them off... just be careful not to rip the rubber though....

If you want anymore info giz a shout, its a dawdle though.....

pauld37

Yeah, no noticeable sound difference , looks alot better though

pauld37

...........use some fairy liquid to get the hooks into the rubber gromets

Dave T-S

Don't want to contradict wrxseeker, but if you want more noise don't bother with PPP or WR Sport back boxes either - you need to go aftermarket, where the world is your ASBO

(Would just mention in the past I have had a MY00 classic with original ScoobySport system and decat, MY01 blobeye with ditto, MY02 STi UK PPP with decat and TSL backbox, and MY05 Forester 2.5 PPP so i'm not just making this up )

wrxseeker

iTrader: (1)

I agree with you but as its a MY05 car he want to keep his warranty intact (like i did) .

Like you say if its pure volume hes after and not worried about warranty the world is his lobster

sgcooby

I doubt you would have warranty problems from changing your backbox. You want to change your centre section aswell to really unleash the burble.

scoobyboy1

iTrader: (16)

STi has one less Catalyst then on the WRX, The uppipe on the WRX still has a cat in it. It might make a bit of a difference of the sound on the STi. But personally if you want a bit of the scooby burble and dont really want a big loud exhaust, go for the Prodrive backbox.

silverscoobydan

CHRIS C201 thanks mate thats exactly what I am looking for (do you think I can get away with reusing the gasket?).

Thanks all for your comments.

I want to keep it OE as I have the warranty to look after for a while longer. The other options were consisdered but too expensive at the moment. The STi back box is in very good nick (1000 miles old) and was only £50 (inc delivery) from ebay.
Eventually I will get a full system and a de-cat. For now the Sti will do nicely.

Thanks
Dan

chris_c201

Dan,

No bother...

I re-used my gaskets and it seems fine.... its a good first cheap mod....

I'm planning a full de-cat but still won't be changing the back-box, had a really loud exhaust before and its nice in small doses but gets very tiresome, full de-cat with the STi BB should be fine for me!!

P.S = If you need any more info or got any questions giz a shout.

Cheers
Chris

swtmerce

Hi there. I've just done this on my MY03 and concur that there's no sound difference, just looks better. I'm gonna change the resonator section next for a non-resonated one (obviously) to see how that changes the sound. BTW, Don't forget to use some gasket sealant!