Yes, very mundane, I know; having never done an exhaust before,
what would I need to change the backbox ?

Gasket and a few bolts ? (assuming the old ones are seized or useless)

I'll be attempting to put a std P1 BB on a MY99.

 

Stanmo,

I did the very same thing - added a std P1 (stamped STI) BB to my MY99 RB5.

All you need is to jack the rear of the car up to get enough room to work under it. I used a trolley jack under the rear diff (added a thick piece of wood to stop the jack damaging the diff).

I then put some axle stands under the rear (used the little triangle things) next to the jacking points in front of the rear wheels.

Then it was just a case of undoing the two bolts holding the BB to the centre and plenty of WD40 (or washing-up liquid) to loosen the rubber exhaust supports. AFAIK the bolts aren't anything special, so it's no big deal if they break. Just have a couple of 10mm (??) bolts to hand.

There wasn't (or isn't) a gasket on my car, so I used some exhaust sealer (from Halfords) to make the new connection air-tight.

Considering I'm completely useless when it comes to cars, it only took me about 30mins. Half of that was standing around scratching my head figuring out the best way to go about it

Stefan

 

There should have been a gasket, they are just welded to the original stuff sometimes. You just have to pick them off carefully. Easiest is to get a gasket just in case, and bolts if you desire.

 

Ahh, that old DIY mantra, preparation is everything...
Thanks for the responses.

ozzy - Did it make a difference to your car ? ie. less restrictive ?

 

Stanmo,

Not enough that I noticed. It certainly helped with the sound and got rid of those orrible pea-shooters Not loud or obtrusive, just a nice burble. Everyone who has seen my car always commented that it must have some stealth device fitted it's that quiet. I've now got a TSL de-cat DP and centre with the P1 backbox and it's still pretty quiet unless it's on full-chat

If the you're still running the OEM dp and OEM centre, then I'd be shocked if you could feel the difference.

I noticed a slight increase when I fitted a de-cat centre, but the real kick in the pants was the downpipe; major

Definietly wasn't any gasket between the OEM centre and OEM BB There was one on the DP though.

Stefan

 

Right bugger on mine - get lots of WD40 on them and leave for 30 to 40 minutes before even trying to shift the little buggers.