Requires minimum Game Version 6.0 and All DLC (up to Kingdom End), unless the game can handle patches that goes to missing DLC files. 

=== Summary ===
--- Boost Properties Change ---
Changes made that boosting still cost shield (you can't boost on empty), but it won't shred your entire shield in seconds. Especially useful for your boost-loving AI subordinates.
With increased boost multiplier L/XL Ships can boost up to normal flying speed (280~ m/s; depending on ship and engine) and burning 25% shield now gives somewhat decent distance coverage.
In theory, by using boost a L/XL ship is no longer a sitting duck under fighter swarm and can limp away somewhere faster than before (provided it can sustain its shield).

--- Travel Properties Change (L/XL Engine) ---
Vanilla L/XL Travel Engine has lower shield duration, slightly higher attack & release properties, and meager increase of travel multiplier in comparison to its L/XL All-Round Engine counterpart.
In addition of meager speed multiplier increase, L/XL Travel Engine also has less 'Forward Thrust', which translates to lower base speed after being multiplied by ship drag/mass/engine count modifiers.
Weird/faulty game design or decision? Not sure, but this results in weirdly pathetic travel speed margin of L/XL Travel Engine while having disadvantages on many aspects against its AllRound Engine counterpart.
IMO it makes the player choice of Engine leans toward AllRound Engine on almost any situation.
Changes made in hope that decision to use L/XL Travel Engine actually has benefit, rather than just for looks/variety/lore/role's sake.
Generally, Travel Engine has about 20-40% more thrust than its AllRound counterparts on S/M Engine; These changes aim to achieve close to that ratio for L/XL Engine.
Vanilla value for travel charge of L(20)/XL(30) Engine is excruciating. Reduce value by lots, but still not quick enough for insta-getaway.

=== Details ===
--Vanilla Stat--
TER S/M Combat: boost duration = 19
S/M Combat: boost duration = 10
S/M AllRound: boost duration = 7
S/M Travel: boost duration = 4
L/XL AllRound: boost duration = 29, boost thrust = 2 (1.6 for SPL)
L/XL Travel: boost duration = 26, boost thrust = 2 (1.6 for SPL)

--Boost Tune-up--
GEN/ARG/TEL/PAR/SPL/BOR/PIR
S/M: Improve boost duration by (Vanilla x4) +10
L/XL: Improve boost duration by (Vanilla x4) +10, Improve boost thrust multiplier by 100%

TER S/M
Combat: Improve boost duration by ((Vanilla-4) x4) +10; reason combat boost has 19 base (twice value of standard combat(10))
AllRound: Improve boost duration by ((Vanilla+3) x4) +10; subsidize from combat to fit theme (booster specialist)
Travel: Improve boost duration by ((Vanilla+1) x4) +10; subsidize from combat to fit theme (booster specialist)

TER L/XL
Now there is reason to choose TER L/XL Engine. Travel Engine shield duration is increased around 23% and 40% increase for AllRound Engine.
AllRound: Improve boost duration by ((Vanilla x4 x10) /7) +10; calculated from subsidized M TER/ARG ratio. Improve boost thrust multiplier by 100%
Travel: Improve boost duration by ((Vanilla x4 x5) /4) +10; calculated from subsidized M TER/ARG ratio. Improve boost thrust multiplier by 100%

--L/XL Travel Tune-up--
Adjusted travel charge for L(6)/XL(9) AllRound Engine and L(8)/XL(11) Travel Engine.
Increase L/XL AllRound Engine travel thrust multiplier by 2 or about 6-10% increase.
Increase L/XL travel thrust multiplier based on M AllRound/Travel engine travel thrust ratio.
The lower forward thrust value of L/XL Travel Engine has, also taken into account and calculated in the tune-up formula.

M AllRound/Travel Engine travel thrust ratio:
ARG      PAR      TEL      SPL      TER
12/ 9     11/ 8    12/ 9    7/ 5      12/10

Tuned L/XL Thrust:
ARG                PAR                  TEL                 SPL                  TER
AllRound 33   AllRound 31     AllRound 33   AllRound 14     AllRound 35
/Travel 46.2   /Travel 44.76   /Travel 46.2    /Travel 20.58   /Travel 44.1

PIR only has XL AllRound Engine. Thrust: AllRound 35
XEN only has L/XL AllRound Engines. Thrust: AllRound 27

BOR (Exception)
Vanilla Travel properties value of L/XL BOR Engines are weird for whatever reason: 
1. L BOR AllRound Engine Attack (Time to reach top speed) is 75, while its Travel counterpart value is 178.5 (ain't nobody got time fo that).
2. L BOR AllRound Engine Charge is 15, while its Travel counterpart value is 0 (on other race, AllRound Engine has lower charge than Travel Engine, Combat Engine is 0).
3. L BOR AllRound Engine Release (Time to reach full stop) is 23, while its Travel counterpart value is 1.25.
For now, I decided to leave it as is (vanilla) until I feel the need to adjust those values.

=== Lite Version ===
!!! Do Not Install Along with Main Mod !!!
Choose to use Main or Lite (It will overwrite each other when installed)

--- Boost Properties Change ---
Same as Main Mod
-- L/XL Travel Tune-up (Lite) --
For those who think main patch upgrade was too much (PAR Engine on certain ship can reach 9K).
Halve vanilla travel charge time for both L(10)/XL(15) AllRound Engine and Travel Engine.
Removed the +2 AllRound Engine travel thrust multiplier; Use vanilla value.
Remember that L/XL Travel Engine has lower forward thrust; the thrust multiplier for Travel Engine will be adjusted to produce the same total thrust when AllRound Engine is multiplied by Travel Engine thrust multiplier.

Simply put the formula is like this :
Adjusted Travel multiplier = (AllRound forward thrust x  Travel multiplier) / Travel forward thrust

Vanilla L/XL travel thrust multiplier:
ARG                  PAR                   TEL                   SPL                   TER
AllRound 31     AllRound 29     AllRound 31     AllRound 12     AllRound 33
/Travel 33        /Travel 31         /Travel 33        /Travel 14         /Travel 35

Tuned L/XL travel thrust multiplier (Lite):
ARG                  PAR                   TEL                   SPL                   TER
AllRound 31     AllRound 29     AllRound 31     AllRound 12     AllRound 33
/Travel 34.65   /Travel 32.55   /Travel 34.65   /Travel 14.7     /Travel 36.75

Max Travel Speed(m/s) Comparison with TER XL Engine MK I on an Asgard:
Vanilla: AllRound (2,334) vs Travel (2,358)
Tuned: AllRound (2,476) vs Travel (2,971)
Lite: AllRound (2,334) vs Travel (2,475)

=== Compatibility ===
Properties and patches based on Vanilla 6.0 and All DLC up to Kingdom End.
Compatible with any mods unless updating the same attribute; This mod only alters Boost duration, Boost thrust, Travel charge (L/XL) and Travel Thrust (L/XL) on Ship Engines.
No VROs, don't even ask (why? they already cover engines). If you like/prefer these changes here, adjust the VROs values yourself using this mod as reference.

=== Re-upload/Re-publish ===
NexusMods only
Free to modify and reupload, give credit where credit is due.

=== Credits ===
Original mod and inspiration references:
Dsiable boost by Grimskull - mods/948
Increase boost duration by ST - mods/1257
Reduced engine travel charge times by Toazd - mods/1077