[mwebb]

so what is it that you are trying to monitor ?
what system ?
what car ?
OBD1 ? OBD2 ? Diesel ? Gasoline ?

it matters . i suggest that you pick only one to start with .
there will be a learning curve .

bottom line
your monitoring of the end result will have little to no effect on FE
if the system is operating as designed
you will not be able change anything that will create an improvement

there is much to be learned before you spend 1 penny on any test equipment

i suggest
you re focus your leaRning curve to zero in on DSO s - there is more to be leaRned and more to be tested with scopes than with a 5gas ,
do not waste your time with a 4gas
again
spend no money ... yet

navigate to Autonerdz then ACE MISFIRE Detective then ATS Escope - study what is listed in the forums and tutorials in those sites

in ATS there are also tutorials related to the use of the 5gas , the information can be applied to any 5gas

in AMD and ATS information on the use of pressure transducers combined with scopes

then
think on it for a while , it will be a journey , a long journey .

Pico6 is the best choice the most resolution the best price
the greatest versatility

but
it is a personal choice , like choosing a pair of boots or a firearm
you have to be comfortable with the choice