Most guys I have seen doing heavy declines,bounce the weight off their lower ribcage/ diaphragm area.
You can see how much more pec involvement declines to the neck would be just by mimicking the movement from your chair at home...........way more of a stretch on the pecs.
I`d advise doing it at the end of a chest workout where lighter weight will feel pretty tough due to the pecs being exhausted from the earlier work performed.
Or,just do fucking Dips!
Wes... guys who are very advanced like you know how to do them. you know what weight to use and just where to hit that sweet spot. Most would be better doing decline press but not to the neck. Itīs like Steve on the Mature thread...his chest-tri workout with his weights used would kill me.