I've recently talked about few turbo guys about similar decision (dual throttle bodies vs. dual plenums with single throttle body) and single throttle body won hands down. I don't yet have any personal experience with turboed edi's but should have next summer, hopefully I'm on the right track with the following arguments
Here's few reasons I've been told against dual throttle bodies:
- Controlling it with MAP is going to be difficult (plumbing MAP from 4-to-1 piping from each intake pipe, then again slower response for quick changes that has to be compensated with TPS)
- With mainly TPS based control, you'll need to compensate the boost somehow
- Need for linkage
- (sync should be easy with TPS's on both sides)
- Plumbing is way harder if you're not going to find readily available solution
- Needs more space, at least more height
Of course there's the brighter side also, for example
- Cool looks!
- Impressive n/a throttle response
- Maybe more top end power?
- Possibility to run injectors straight above the velocity stacks, too bad no-one can see them (...plenums made with windows?)
Dirty'n'cheap alternative:
- Strip your Dell's and plug gas holes
- Install TPS's to both carbs (now throttle bodies)
- Change or modify manifolds with injector seats
- As you have already the plumbing, linkage etc, only problem is going to be accurate enough measuring of the air going into engine
From my friends tale, I've reasoned that with n/a engine, TPS controlled EFI with dual throttle bodies is easier and accurate for very good results. Varying intake pressure makes it more difficult.