I have never had a brake booster on any of my disc brake minis previously. The one I have now came with one fitted and is getting the vacuum from the manifold, which was a goose neck style for a Dellorto. The car is running 8.4 Discs. I am now fitting a Russell Engineering manifold which doesn't have the option for the vacuum.
I was wondering about opinions on whether the booster should be retained or I should not fit it?

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1975 1310cc Street Mini Custom
1974 Leyland Mini daily driver
2008 Cooper S R55 Clubman

As you have the servo already I'd just tap the manifold somewhere to suit. You only need to do 1 side. Unless you want to do the other port as well, and run a PCV valve into it. Works for me...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Boosters are personal choice.
Some people like them, others dont.
I haven't got one in my car which suits me fine........for the first 30 minutes of driving.


That said, I wouldn't run hard / sport pads without one though.

I run S brakes with Greenstuffs and no booster, and to me it's fine. It pulls 1.0G on a brake test.
But I let my Bogandore neighbour drive it once and he said f***, where's the brakes!!

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

If I tap in a vac line will it affect the flow rate of the manifold? I don't mind a hard pedal. I am thinking of going non boosted and if I don't like it then add the booster later.
The last disc brake set up was Cooper S non boosted. Seemed alright for the year or so I had the Mini for as a daily driver.

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1975 1310cc Street Mini Custom
1974 Leyland Mini daily driver
2008 Cooper S R55 Clubman

Nope it won't affect flow under power. It only pulls vacuum when you have your foot on the brakes.
The vacuum is then held in the booster by a check valve at its hose connection.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

That's interesting/good to know. The performance test here for a low volume modified vehicle (what you guys call 'engineered') is .65G, with 68kg force on the pedal causing maximum breaking effect.