What are the pro’s to Twin Plug Heads ? What sort of performance changes ? Any cons ? Do they work for 3.0 / 3.2 / or 3.4 ?

@ Soko121 - there are other threads on this forum debating the benefits. I am no expert but basically twin plugs allow more complete combustion, allow higher compression engine on pump gas. You can also go coil on plug and avoid distributors and have a clean highly efficient set-up. There are a lot of pros and the biggest con is cost. Typically going twin plug would go along with higher compression pistons, ITBs, cams, porting heads. I'm in the middle of a twin plug 3.0 to 3.2SS conversion. Not cheap but definitely improved performance. TLDR: better performance and compression at the expense of cost.

Coil on Plug (CoP) works great on single plug setups...most CoP setups are single plug.

Craig Garrett did a great job on my 2.8
 

I think it is important to support our parts makers and machinist aficionados that do good work for our old cars.
Craig has good/prompt communication, excellent machine work, packaging and Good pricing.
He sourced better quality guides, did a good valve job/head resurfacing and twin plug work for my dad's old 74.
For sure, there are a lot of good people out there, and Craig is one of them.
He took my 32mm intakes to 37.
Use him again in a heart beat.
chris

FWIW I also had a great experience with Craig at G2.
I echo everything above.

Chris in TX

Craig Garrett (Cgarr)........excellent work, great turn time, pricing, etc.