Yeah cost effective ships stay below Core7... Core9 is a nice sweet spot.... then everything above is for combat or big sized (heavy) ships... in my opinion

ahhh ok thats what i thought as id seen many builds skip the basic two basic extenders and just go into puttin improved and advanced in i always use the basic and go on from the default 2 basic 2 improved 4 advanced 5 superior and up to 3 maybe 4 auxilary cores even though it says can have 6 and i have 1 quantum cpu extender altough it states upto 8 but i dont see many ships needing that much cpu

For the base Vanilla game there is just 4 Tiers, gaining that tier's CPU when you installed the required cores.
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However in Reforged Eden 2 (RE2) each core you add will increase the overall core count.... So a Core13 has the base core plus 12 more. Most builders will stack in order from cheaper cores up... but there are a few instances where you might see an exception, like a Core 5 that skipped the cheaper cores to balance CPU higher than a normal Core 5... but those exceptions usually confuse people... the vast majority of builders and my creations stack the cores in their proper cost order.

Fuji i know this is proberbly a stupid question im asking but how do you work out the core as i have no idea i also admit i have no idea what core i upgraded the angelica vanguard too