The Yak-1 kit originally manufactured by Accurate Miniatures and now re-boxed by Eduard is a fine little kit but could certainly use a bit of aftermarket sparkle with this Quickboost exhaust kit. The original kit parts are ok but lack the bored out exhaust stubs.
The Quickboost kit contains a pair of well molded exhaust parts in grey colored resin. Removal from the pour stub is easy by simply making a few scores with your favorite sharp hobby knife. Please be careful - it is easy to score through the part (ask me how I know), and slice the part in half. Once separated from the pour stubs, a few scrapes with my hobby blade cleaned up the part and I was able to place it relatively easily in the fuselage opening. These two parts have a good fit and it looks good when installed.