Yep, they're the ones.
That's a good price actually! Just run it on them.
You say that a good nitro engine is £250. How often do you need to replace that? Every two seasons if you're lucky! These packs (say 4 in total) will last around 4 seasons, but cost £170 from the source you used.
Not to mention fuel costs (£30 a gallon).
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