Ok.. so here's my revision for Gundanium Alloy superstructure and armour and Luna Titanium.
Gundanium Alloy Superstructure (PL8-9)
A unique compound which can only be produced in the zero-gravity conditions of space. In addition to its incredible strength--several times the strength and heat-resistance of titanium, Gundanium alloy is electrically non-conductive and cannot be detected by radar, is highly heat-resistant and virtually immune to corrosion. However, this material is expensive and difficult to manufacture, making it unfeasible for mass production. The material makes the mecha difficult to detect at long range with conventional radar and MAD sensors. Opposing units trying to detect a mecha with gundanium alloy superstructure take a -5 penalty on their computer use checks if they are using Class I, II or III sensor suites. Class IV and higher are unaffected, gains Ion Resistance (see d20 Future Tech) 10, +50 Hit points, but repair checks, cost and time increases by 50%.
Hardness: 35, 50 vs kinetic attacks (ballistic, slashing, piercing, bludgeoning, concussion, etc).
Speed Bonus: +0 ft
Base Purchase Modifier: +10
Gundanium Alloy Armour (PL8-9)
Gundanium alloy can also be used as armour for a mech, making it very resistant to damage. If a mech also has a gundanium alloy superstructure, it is even more resistant and difficult to track. Inherent stealth properties of gundanium give opposing units trying to detect the mech take a -5 penalty on their Computer Use checks if they are using a Class I to III sensor suites, higher suites are not affected. Mech is immune to acid damage, damage from planetary re-entry is reduced by 75%, gains ion resistance 10, gains +50 Hit Points, Repair checks, cost and time increases by 50%.
Equipment Bonus: +14
Armour Penalty: -7
Speed Penalty: -5 ft
Purchase DC: 19 +1/2 the mecha's base purchase DC.
Special Bonus for having both Gundanium Superstructure and Armour
Having a mech built using both gundanium alloy in the superstructure and armour makes it an extremely durable, and expensive. Such a mech imposes a -15 to Computer Use checks to opposing units trying to detect the mech (overrides the -5 for either armour or superstructure), has Ion Resistance 20 (overrides the 10 for armour or superstructures), gains an additional +20 Hit Points.
Luna TitaniumSuperstructure (PL6-7)
Luna Titanium wasdeveloped as a new light weight but durable alternative to titanium or steelfor the construction of mechs. Although proven to be quite effective inresisting physical damage, and being light weight, it is expensive anddifficult to work with. Repair checks, cost and time increase by 25%
Hardness: 20, 40 vskinetic attacks (ballistic, slashing, piercing, bludgeoning, concussion,etc).
Speed Bonus: +0 ft
Base Purchase Modifier: +7
Luna Titanium Armour(PL6-7)
Luna titanium can also be used as armour for a mech, making it very resistantto damage, and is very light. Repair checks and time increases by50%.
Equipment Bonus: +8
Armour Penalty: -5
Speed Penalty: +5 ft
Purchase DC: 13 +1/2 the mecha's base purchase DC.