From way back when I think it applies here

Level 1

Reactors :
12-13k Regeneration Rates.

Armor:
Mass under 750
Armor 190+

Ditch Everything Else.

Level 2

Reactors :
13k-14k minimum regeneration
Mass under 1200.

Capacitors:
Mass under 1.4k
Drain under 800
Energy Pool with 950+
Regeneration Rates 38+ Since these must be two stat items, don't shy away from caps that have 30+ gen if the other stat(s) are solid

Armor:
Mass under 1200
Armor 290+

Boosters: These boosters are a great addition to throw into your loadouts until you can get a crafted reward booster.

Level 3

Reactors:
Mass under 2k
Generation 14k+
Look for "Koensayr Mark II Supernova Reactor" and "Kuat Systems Engineering LX-21"

Armor:
Mass under 1700
Armor 490+

Ditch Anything Else.

Level 4

Reactors:
Masses under 4000
Generation 15k+

Engines: In my opinion, level 4 engines are not worth RE'ing. They are too slow with too little benefit and they aren't used long enough to be necessary to the grind. It is far more prudent to use a crafted engine.
Mass under 3800
Drain under 1600
Speed 68+
YPR 62+

Capacitors:
Look for these "brands" of capacitors for these stats:
Gallant A1 - low masses, low drains
Gallofree LT-22 - high regens
Corellian Tuned Mark II & Special BJN-825s - high pools
Qualdex Conservator Q3 - high regens, but LT-22s are usually better bets
Drain under 700
Cap Energy 1000+
Recharge Rate 40+
Mass under 3k

Armor:
Armor 600+
Mass look for Sienar Flight Systems Light Military Grade Durasteel which has 1986

Boosters:
Look for 3 specific names when building a level 4 booster: These are rewarded to pilots when running tier 2 missions. Also very common drops from convoys as well.

• Mandalmotors M-Series
• Novaldex Hypernova
• Sienar Special Ion Booster

Using these boosters go for these stats:
Energy 1980
Mass under 3100
Drain under 500
Consumption Rate under 145
Speed around 26+

Ditch Everything Else.

Level 5

Weapons :
Drain under 2k
Min Dam 1150+
Max Dam 1700+
Vs Shields .64x+
Vs. Armor .64x +
EPS under 22
Refire under .330
Mass Under 6000

Shields:
Front and Back HP 1100+
Mass Under 6.5k
Drain Under 2000
Regen 8+

Armor:
Mass under 3k
Armor 950+

Reactor:
Mass under 5.5k For really good projects you are trying to get under 4k after RE (see generation below)
Generation 14k+ This number is not correct. 14k drops are excessively common. I destroy everything below 17k and have a dozen or so over 18k. Ideally you are looking for something that will get as close to 20k gen after RE as possible.

Ditch Everything Else.

Level 6

Engines:
Drain under 1400
Mass under 9400
YPR 67.5+ (do not go lower!)
Speed 86+ "shooting star" engines from convoys commonly drop ETS in the mid 80s.

Capacitors:
Drain under 700
Mass look for 2 brands: "Mon Calamari Modified Heavy" and "Qualdex Heavy Capacitor Array."
Mass under 8k
Capacitor Energy 1200+
Recharge Rate look for Qualdex Conservator QX2s w/ 46+

Weapons:
Drain under 1800
Mass under 10k
Min Dam 1700+
Max Dam 2600+
Vs Shields & Armor .660+
EPS 27 and under This is a little high. I keep anything 25 and lower
Refire .400 and lower

Armor:
Look for Corellian Triplate pieces
Armor 1200+
Mass 6k and under

Shields:
Front and Back HP 1400+
Mass Under 11.5k
Drain Under 1950
Regen 10+

Reactors:
Mass under 9k, preferably under 8k
Gen 24,500 and higher

Ditch Everything Else.

Level 7

Reactors:
For the most part these are junk. However, keep an eye out because occasionally they can drop with really, really high generation rates. I?m talking 25k to 50k. These are definitely keepers and will be needed if you want to outfit a good TIE Oppressor or a Firespray. The brand to keep an eye out for is: Slayn & Korpil "Vortex" Mk3. Re-Engineer it with a Level 7 with around 15k mass or lower and you have a truly exceptional reactor.

There are some good and some outdated points on the info above about level 7 reactors. These are the most coveted reactors for large multi gun ships like heavy Xs and Firesprays if done correctly. As the info above states, mass below 15k is good. This is not exceptionally rare. I have only been looting for about 6 weeks now and have pulled a 12k and a 10k mass. Gen, anything over 26k is usable for 15k masses. Anything with mass below that should be held for 30k and above.

Shields:
Hitpoints 1800+ (Nym?s Starmap gives Protect-O Net Shields good for this) This quest is repeatable. Get rid of anything less than 2100 F/B
Mass under 16500
Drain under 2000
Regen 14+

Weapons:
There are only really two weapons you need to concern yourself with here for damage:
Sienar Flight Systems "Boltdriver" & Ionic Pulse Weapon
The Boltdriver is an Imperial-awarded weapon. It's always 1910.x-295x.x.
The Ionic Pulse, awarded by Eyma on Kashyyyk is a lot more varied.
Drain under 2k
Mass under 15k
Vs Shields & Armor .600 +
EPS 24 and under
Refire .330 and lower

Armor

Keep your eye out for armor slabs. I'd hang on to any slab with 1500 or higher protection. Sometimes armor slabs can drop from all levels with really excessively low mass. It is good to keep an eye out for those two possibilities.

Ditch everything else.

Level 8

Engines:
Nym's Starmap Quest gives a level 8 engine called the Quantum Ion Drive that can reach 100+ speeds
This quest is repeatable. Get rid of anything that is not ETS 92 or higher.
PYR 70+ is nice but you really want the rare 71.5+ to get a RE engine with 75.0 ypr
Drain under 1450
Mass under 25k

Weapons:
The Borstel Disruptor (and its twin cousin the Incom Tri-Cannon, a Rebel Tier 4 reward) is hands down, pound for pound, the very best weapon in game. This beauty is a reward for neutral pilots at Box 16. It has nearly unbeatable Damage and an EPS that will never be matched by anything else you craft or loot. I believe it is worth it to take your toon and all your alts up the neutral tree just to get this gun; it is that good. Do not RE any Level 8 guns without the Borstel. With a Borstel, the stats you want are:
EPS and Damage will be covered by the Borstel
Drain under 2k
Mass under 25k I recommend holding out for 25k or lower. I personally don't even start RE'ing 8's until I find something in the low 25k range
Refire .400 and under This number is a bit low. For really good projects I would work for getting lower than .400 but in all actuality, .405 works just fine. I personally keep .410 and lower.
VS Shields & Armor .650+ is probably a better option and not terribly uncommon. .660 is the cut off for good projects

Reactors:
Same as the level 7's. Most are too heavy to be worth it, but if you loot one called the Kuat RCT-Z it can have generation rates from 30k-50k+. Pair it with a Level 8 with 23k-24k mass and that is the best you can get. I would say try to get that mass below 20k. It's not common to work a level 8 reactor because they just tend to be too heavy but if a superior gen drops in the 40k range or higher and the mass can be around 18k or less you will have a wicked powerhouse for your heavy. I

Shields:
Drain 2000 and lower
Mass 28k and lower
Regen 14+
Front & Back Hitpoints 2433 (Tier 4 reward shield available in all squadrons)

Armor:
Hitpoints 1900+; Nym?s Starmap gives a nice 1920 piece of armor
Mass under 13k

Ditch Everything Else.

Level 9

Weapons:
Drain under 2000
Mass 35k-40k
Min Damage 2200+
Max Damage 3500+
EPS 24 and under
VS Shields & Armor .6xx+
Refire under .33x

The thing about 9 weapons is that in order to be useful when compared to an RE'd 8, they must have exceptional stats. If you are going to RE a 9 I would say hold out for a mass 36k or lower and get that refire down as low as possible since that is really the only advantage to a 9.

Ditch Everything Else. Do NOT ditch everything else. Keep your eye out for armor slabs. I'd hang on to any slab with 1900 or higher protection. Sometimes armor slabs can drop from all levels with really excessively low mass. It is good to keep an eye out for those two possibilities.

Level 10

Engines:
Mass under 45k
YPR 77+ needed to RE 80's I changed this to 77 min just based on the amount of 77's I've looted. These are pretty common so I quit keeping anything less than 77.
Speed 90+
Drain under 1500

Shields:
Drain under 2000
Mass under 50k
Hitpoints 2500+ With convoys now, these can drop into the high 3k's. I would use anything starting at 2900 and higher.
Regen 16+

Weapons:
Drain under 2k
Mass in the low 40k's
Min Damage 2700+ I don't use anything less than 2700 and that only for junk projects
Max Damage 4500+ Nyms Starmap is repeatable and the beamrail drops consistently with high damage. 4500 or higher is useable. Anything lower is not worth keeping. Ideally you want something 4700 or higher with over 5k being the coveted parts.
Vs Shields & Armor .700+
EPS around 30.0 and lower 32 is fine for lower quality projects. I keep anything below 32 myself.
Refire around .400 and lower

Armor:
Hitpoints 2300+
Mass under 17k (possible to go much lower with fantastic luck but this is a realistic goal)

Capacitors:
Mass 35k-40k
Drain under 1k
Capacitor Energy 1300+
Recharge Rate 55.x+

Reactors:
Hit points 1100+
Mass 27k and lower
Gen 38k and higher

Boosters: keep anyting 95%+, this will take time!

Ditch Everything Else.