Silver engine is from the 2006 1/25 Revell Dodge Magnum SRT8. Can't be a V-10, as it's only got 4 exhaust ports per side and the instructions state it's a "6.1liter Hemi".
Sorry, I left out the , as my comment was stated in jest. It does look about right for V-10 length, at least compared to the V-8 above it.
It comes back to the "How close to perfect do you want it to be?" idea, which always reminds me of: "Speed costs money. How fast do you want it it be?"
How perfect a kit do you want, and how much are you willing to pay for it? Unfortunately for us, it really doesn't matter, as we are in no position to either create our own mass-produced kit by the thousands nor able to directly influence a company such as Revell as far as kit design and production is concerned. That puts the burden of perfecting the kit on ourselves, once we buy the kit and it's in our hands. The sliding scale of "acceptable error" is different for each company, each model, and each customer/end user, so can we realistically expect a narrow range which all would agree upon?
I understand Brett's "fudging" comment, and while it goes against the "true to scale" mentality to increase the size of an engine so it appears to be in better proportion with the rest of the kit, sometimes it's in the best interest of the business to do so. Maybe not other businesses, maybe not even the business in question's direct competitors, but for the business making the decision, it might be, even if it's for strictly monetary reasons.