Drain waste vent alternatives

Hi there - i currently have a standard waste pipe vent rising up through the attic and roof. i'd like to get the space back that this takes up in the bathroom (its a bit small). Are there any alternative (simple) ways that i could achieve this. Alternatively could i go horizontally through the external wall and then vertically up the outside wall rather than the inside?

Air admittance valves are not a substitute for an open vent stack. There should be an open vent at the end of the drain run to relieve positive pressures and release any build up of sewer gases.

AAVs should only be fitted on secondary stacks as they only relieve negative pressures.

Without an open vent you could end up with sewer gases bubbling back up through your waste traps.
The open vent terminal is set clear of any openings in the building to help keep any sewer gases it releases out of your house.

IIRC you can have as many bends as you like in the 'dry' section of the soil stack (that's the bit above the highest waste connection), and you may even be able to reduce the vent pipe size to 90mm, or maybe even a bit less. I think some have said 75mm is OK.

As building control will probably be interested in any modifications to your soil stack they are probably the best source of information about what they consider permissible.

Thanks Tick.
Please be reassured that i'm not trying to remove my soil stack I was just exploring if there are any alternative methods with current technology or whethere there would be any issues with me running the pipework via alternative routes. Your suggestion that i can have multiple bends is useful thanks!!

aav is fine and not only for the secondry stack.
Look at EN12056-2 En12380
it states that only 1 in 10 stacks have to be open to atmosphere.
The O2 in london doesnt have 1 roof penetration and is vented elsewhere.