Before getting into my mod, I should mention that there is a stock tuning part for the 313 called "Dual Race Exhausts" that adds 5 horsepower to the engine. It shows that the devs do pay attention to the 313. So, I've given the Burnside 313 the tuning parts I believe it deserves. (Horsepower ratings are for each individual part.) Four-barrel carb (171 horsepower): This is the one we've all wanted; it was originally putting out 165 horsepower, but I found that I could get 170 horsepower from my replica 313 in Automation. Three stages of engine block (179, 190, and 230 horsepower): Stage 1: Stage 2: Stage 3: I've also added heavy-duty and ultra-heavy-duty engine blocks to the Burnside 313. With the Stage 3 block, race exhaust, and four-barrel carb, you can now get 279 horsepower from the 313 for all of your early-NASCAR replica Burnsides.