Best M20 stainless manifold & exhaust system

[svenga]

Good Afternoon all,

Exhaust & manifold advice please!.

I have had my 1989 325i convertible for over six months now, and it is time to scrap the cobbled together stainless exhaust system it came with (the front flexi pipe is shot, even before hand it sounded 'interesting'.

I will be looking at a full exhaust system in stainless (I was going towards scorpion as my last e30 had one fitted and it was happy sailing) but would like to hear other opinions, my car is standard bar the wild chip from speed-touch and a K&N panel filter. I am not bothered about tail pipe appearance but more value for money and performance as well as simple fitting (it does not have to sound loud or tuned).

As well as the exhaust system I am leaning more towards changing my exhaust manifold to a six branch stainless, I have done some reading up and found many pros and cons (the ebay specials being nothing but visually nice and pointless, the good ones being scarce or big figures). One issue I have is my e30 is fitted with an e36 steering rack, and is obviously right hand drive.

Apart from BTB (I simply can not not afford one ) can anybody recommend another good stainless manifold which is almost bang for buck and still compatible with an e36 rack fitted.

Any advice or recommendations appreciated!

[Topblag]

I've got a magnex stainless system, including manifolds and it's an easy all in one solution, no issues with mating bananas to exhaust and clears the steering rack easily.

Avoid cheap eBay options at all costs.

[_Dan_]

Hartge manifolds clear e36 rack too

[Gavt]

Does the hartge manifold clear the e46 rack too. Couldn't spot much different about the two racks.
Cheers

[maggspower]

Does the hartge manifold clear the e46 rack too. Couldn't spot much different about the two racks.
Cheers

Yes, they are outwardly the same.

[maggspower]

Just thinking out loud here:

Is there a demand for m20 high quality, high BHP proven, tubular stainless manifold, that works with a rack swap. and is cheaper than BTB???????????

[Gavt]

I'd say so. I have the hartge manifold but if you are thinking about producing a copy to a high standard I think it would sell well as there isn't much option unless you spend ridiculous amounts on btb or are lucky to find a second hand good one.
How cheap are you thinking.

[steve_k]

Just thinking out loud here:

Is there a demand for m20 high quality, high BHP proven, tubular stainless manifold, that works with a rack swap. and is cheaper than BTB???????????

i think there just might be

i had a quote from a place in chesterfield the other year for £2k+ to make a copy of the RD manifold (with X pipe) in stainless steel grade 316.

so if someone could make one like that for less then there'd be a market.

[maggspower]

I'd say so. I have the hartge manifold but if you are thinking about producing a copy to a high standard I think it would sell well as there isn't much option unless you spend ridiculous amounts on btb or are lucky to find a second hand good one.
How cheap are you thinking.

I'm not thinking cheap, I'm thinking cheaper than BTB, its all relative anyway.

If I was to make one, it would have all the holes in the right places, the flanges would be flat, the metalwork would be top draw, it would actually fit, and all the welding would be argon purged tig.

The worst of the cheap ones tick none of the above boxes. The better ones at least fit.

The BTB offering is almost worth the money, however much it currently is, as it is exquisitely made and designed, and its produced in the UK not in some sweatshop in a far flung land, that have no idea of the importance of the length and diameter of the primary pipe or how to make a proper merge collector.

I would only consider making a high quality piece.

[reggid]

There is a market for a cheaper BTB. The BTB works pretty good (IMO mostly due X-pipe position) but isn't ideal either in many details. if you go down this path this is what i would do differently to BTB.

1) The way the tubes come off flange and immediately have a sharp bend make the nuts hard to put on and hinders flow

2) Primaries are 1-5/8" OD which is easily big enough for well over 300bhp so a bit too big on a 170-230bhp engine (most engines fall within this bracket). 1-1/2”a would be better and still work with the big strokers around, but even 1-3/8”a stepping to 1-1/2”a would be even better IMO for smaller engines.

3) Primary length is about 26”a. this tunes a bit high like 7250rpm, something tuning lower would be better so add atleast another 2 or 3”a primary length.