30i exhaust

[therealmc]

Hi. Does anyone have experience of fitting a two back box system (35i style) to a NA 3.0?
I like the look of the Supersprint system but am wondering if there’s a cheaper option such as using the back boxes from a 35i and getting a custom centre X pipe made up.

[therealmc]

UPDATE
Yesterday PowerFlow Brighton linked up the back boxes from a 35i to my 30. Definitely loving the new look.

[Chippie]

Result
Did you fit the rear bumper from the 35?

[Freebster]

Thanks for the update. Does it sound any different? Was it an easy swap or was there some modification needed?

[therealmc]

Hi Chippie, yes I got the insert (not the whole bumper) with the two cutouts from eBay in the right colour and in fantastic condition considering it was second hand. I got a whole, one piece, 35i system from a car breaker website including all heat shields and brackets (delivered) for good price.
Hi Freebster, it’s unlikely to be louder but I’ll check on any change of exhaust note when I go for a drive at the weekend hopefully with the top down. Fitting was simple. They cut the pipes coming out of the centre box, cut the 35 pipes at roughly the same point. The diameters are slightly different so one fits inside the other but they’ve been welded together to avoid potential leaks. I’d already removed the bumper parts, fitted the rear-most bracket and the heat shield and the Powerflow guys expressed surprise how simple it all went together. 3 hours labour was all they charged me.
I’d estimate the final cost as no more than £700 which is considerably less than aftermarket systems. Just need to clean up the tips now.

[Freebster]

Thanks therealmc! Looking forward to hearing what you say about the noise. I’ve always thought that the standard 30i exhaust is a little on the quiet side.

[Mr Tidy]

I don't know about the E89 30i, but while the same engine in my 1st E86 sounded OK a previous owner of my 2nd one had got a custom cat-back system fitted and it sounded so much better! The back box was about half the size of OE.

But in my E90 3 Series it's hard to actually hear it unless you've got your foot planted in the carpet.

I'd also recommend PowerFlow. When I got my MC it had PowerFlow back boxes fitted (which sound awesome BTW) but one of them had a rear hanger missing for some reason.

Anyway I booked it in with their Slough agent and he fabricated and welded one on for £30 - cheapest job it's had so far!

[therealmc]

Correction, it is louder though not hugely which is fine by me. The whole sound is quite different though, much deeper with a nice throb and some crackle on lift off. Remember these are not PowerFlow boxes, they are the standard BMW ones which is why I’m pleasantly surprised. Two and a half hour drive this afternoon and while cruising there was no noticeable droning or other unacceptable noises (Mrs S certainly didn’t complain). Time will tell about durability of the welds where the two systems have been connected but today I am very happy with the result.

[Smartbear]

Correction, it is louder though not hugely which is fine by me. The whole sound is quite different though, much deeper with a nice throb and some crackle on lift off. Remember these are not PowerFlow boxes, they are the standard BMW ones which is why I’m pleasantly surprised. Two and a half hour drive this afternoon and while cruising there was no noticeable droning or other unacceptable noises (Mrs S certainly didn’t complain). Time will tell about durability of the welds where the two systems have been connected but today I am very happy with the result.

On the original car those silencers would have less to do as the turbos themselves reduce exhaust noise
Rob