just changed from the nur spec to the standard backbox earlier and car seems a lot slower,more hesitant when pulling away.i know there is some difference but would it really be that noticeable with just a backbox also seems to take longer for boost to come in,whereas with the blits it started from 3k its now nearer 4 and isnt peaking as much as with the blitz.do i have another problem or could just a backbox swap do that?

 

I wasn't convinced myself that my STi backbox on my classic was a restriction, as I had a sports cat and straight through centre section. But when I swapped this for a Prodrive/WR Sport box off a newage, there was a huge difference. Turbo spool up came 300rpm further down the rev range, compressor surge that I'd been plagued with between 3000-4000rpm almost disappeared. The best £40 I ever spent!

 

Standard back box is hugely restrictive, I fitted a TSL Group N item to keep it quiet, and it's much nicer as stated above.

HTH

DunxC

 

put an afterburner vortex on mine on friday.
wow what a difference

 

As with most of these things, it can be very subjective (you 'can' be easily convinced the car feels quicker if the bb is louder for instance).

However, the only direct comparison I've had (previously I had whole system changed so couldn't say) was swaping my ninja bb for a scoobyworld racebox (bought at right price and sold without loss..). Turbo response definitely seemed a bit muted. I therefore changed back two days later..

Obviously this could have been a placebo effect, as I didn't bother with any scientific testing, which is the only way to be certain. The general consensus is that a bb doesn't effect performance, although most people seem to find otherwise.

Why do prodrive change them with PPP, is it just to regain some burble..?

 

Well my Prodrive box has been great. When you compare the STi with the WR Sport, you can see a huge difference in how restrictive they are. I was all ready to just enjoy the slightly more burbly exhaust note, and was not expecting it to make any difference to performance. But it was like night and day - having known exactly at what point my turbo hit 1 bar and full boost in 4th, to have it suddenly come in at under 3k revs was a revelation. As was the sudden lack of chuff-chuff compressor surge.

 

Hey silent, what's the noise difference between the standard box and Prodrive one? I had a Power Engineering T75 backbox fitted a couple of weeks ago and while it's a nice sound, it's a little on the loud side for me!

cheers
Slim

 

changed my prodrive backbox to a ninja2 and can feel a difference, even get the old flame thrower effect now accordign to my mate....

 

Slim - I'm no fan of loud exhausts, even if they're necessary in some cases to get best flow - been there, done that, worn the t-shirt and been thrown off the 'Ring for it LOL. I was happy with my standard STi box, when I first put the Prodrive box on it was noticeably deeper at idle from outside and you could definitely hear the difference inside as well. It sounded wicked, truth be told, although at first I wasn't sure about it. Within a day or two I got used to the different sound - a little louder and a lot more burbly/deeper. I wouldn't go back, put it that way, and the wife hasn't noticed either.

 

Neither am I, and I'm a little too old to be drawing attention to myself with loud exhausts too! I'm looking at replacing the T75 with an H&S backbox, the one with the twin pipes. If anyone's heard one of these, I'd be grateful for any opinion of the noise levels, sound etc.

DunxC, how's the noise level of the TSL group N compared to the oem backbox?

Cheers
Slim

 

I thought most H&S backboxes were pretty loud tbh mate, might be wrong, try a ninja if not, im the same, don't like anything too bad, but the ninja has the looks and the nice burble without being daft loud.

 

The deed is done, just ordered an H&S de-cat centre pipe with extra silencer and back box with twin pipes. That should keep the bhp to a max and the noise to a respectable level, but also means they'll be a Power Engineering T75 backbox going cheap when the H&S bits arrive.

Slim

 

It is louder than std and Prodrive back boxes, but hardly enough to get noticed in NORMAL driving.... a bit fruity on WOT, but nice and quiet on the motorway.

Appears I'm too late !

LOL

DunxC