Disclaimer: This obviously pertains to the making history DLC/Expansion

A bold statement I know. But hear me out.

The Whiplash has decently higher ISP than the Rapier engine does in air mode. It's also lighter, and cheaper than the Rapier. The Whiplash can get your plane up to Mach 3 if flown correctly on less fuel, as well.

The Skiff is a very good rocket engine. Like, crazy good. It's got the standard ISP of any of the 1.25 meter parts ASL of 265. But more than that it has a gimbal, costs only slightly more than the Swivel, and both has more thrust than and weighs less than the reliant Rapier. But its* real shining feature is that it goes all the way up to 330 ISP in vacuum, which is higher than all the other ground-to-space engines and approaches the effectiveness of the base-game's vacuum-only engines.

Basically, the Skiff engine, much like the J2 engine, is just utterly godlike.

So, by putting a few whiplashes and two skiffs on a small Spaceplane it's possible to achieve Higher Thrust about equivalent or slightly higher and Higher ISP than two RAPIERs. All while costing less or equal to the two RAPIERs, and having only slightly higher mass which is more than offset by the vastly better performance.

Thoughts?

Edit: Saying it's higher thrust is wrong.

Edits: Some spelling errors and fixing my being dumb.