Report:
-Thrusters and power plant upgraded. Maneuver ability has gone up considerably.
-Two med slots are multi cannon'ed, both same fire group.
-Two small slots are laser'ed, same group.
At least %25 percent higher efficiency.
Will try to do a few navy missions to try them more.
Next step: Upgrade thrusters even more, upgrade shields and put military hull plating.
Chaff is hard to use though, changing modules in the middle of the fight is not quick enough.
Yeah, forget about using chaff via a fire group (i.e. firing chaff via the Primary/Secondary triggers) - unless you have all your weapons bound to the Primary trigger (not a bad option, to be fair!) and the chaff bound to the Secondary. You don't want to be switching fire groups needlessly in the middle of a fight, you'll be busy enough as it is. Assuming you're playing on PC, you can set a direct binding to deploy chaff and so it's always available without switching firegroups. (Edit - I've just seen your comment about playing on PS4, sorry. In that case, I'd make sure you have one firegroup with all 4 weapons on the Primary and your chaff on the Secondary and you're good).
Personally, I've stopped using chaff, as I've never found it massively effective; and now use Shield Cell Banks instead (in case you don't know, if you trigger these before your shields drop, they recharge them back up to/near full strength). I find them much more useful BUT firing an SCB generates a lot of heat, so you either need a cool running ship, or you need to carry a heatsink launcher as well. You might struggle to find space on a smaller ship like the Viper.
p.s. Previously when fighting in a Viper, I used to have one firegroup for lasers and a second with lasers & multicannons once their shields came down. While that's a fun way to fight, it's quicker just to have one firegroup with all weapons on it and always hit them with everything. How well that works, depends on your distributor and how you allocate your pips. If you only put one or two pips to weapons, you might find firing all 4 all the time is too much distributor draw (this is where using multicannons helps, plus the efficient mods on the weapons, plus your choice of distributor mod).