[Double Venom]

Hmmm,
OK, so it is a re-build. 'DV' (DoubleVenom Cobra) used a 3/4" spacer plate between the headers and the side pipes. The spacer plate was used to hold a "Bung" for an 02 sensor! ??

Second thought, your spacer plate does NOT need to have a "Four' Hole Pattern in it! Just a solid 3/4" plate cut/milled out to the outside size of the headers/collector.
Didn't know if that configuration or lack of it would allow the pipes to work properly???

A lot of professional testing, Three different Dyno's and the only thing for what ever reason was an in increase of 3 (Three) RWHP and the sound was awesome-for a Viper Engine!

Food for thought, hey? Both sides 'should be done the same'!