cost for 3.4 twin plug conversion?
 

Whats a ballpark figure to convert a 3.2 to a Mahle 3.4 twin plug complete setup including ignition signal splitter ?

I looked into this recently, and came up with needing the following:

twin distributor
heads and valve covers machined for twin plug
6 extra plug wires
ignition control unit
custom chip

I stopped when I found a twin plug distributor for ~$2500

you might want to contact sal carceller (scarceller on pelican) - he's reverse engineered the andial splitter electronics, can program the right chips and has experience from doing a number of these for other. Seems the real question here is what is the delta between a traditional rebuild/top end (or single plug 3.4 setup) and a dual plug 3.4 -- also, you might want to look into going up to 3.5 -- if buying p&c either way, the $ bump isn't that high to get the case spigots machined and, since a 3.4 is just under 3.4 liters and a 3.5 is just over 3.5 liters, there's a fair bit of potential to be had. Also, not sure where the $2500 distributor cost is coming from, 964 setups run around $1k used and there are other options available as well

There are other options out there other than the Andial splitter. The splitter does just that, splits the spark. It is very weak. I used 2 Crane HI 6 ignitions on my 993.

What are the reasons more people don't do the 964 993 twin distributor conversions? And please describe what is involved in using one of those. I think many people did that in the past but the details have been few and far between. It looks cost effective but you don't get a 12 plug distributor cap along with its bragging rights.

Cheapest version is obviously using two 3x2 Bosch coilpacks (~100 usd each) and MS or VEMS standalone. Those would cost around 1000 euros, VEMS comes with a running map.