Not to be mean but restrictions on fuel? In racing? Really? Since the heat extracted and the heat rejected in an internal combustion engine is essentially constant on a percentage basis, the way to get more power is to flow more air through the engine. An air to fuel ration of 12 or 12.5 to 1 is pretty much ideal for energy extraction (alcohol fuel air ratios are lower) so it should come as no suprise that power drops as fuel is restricted. So don’t expect speeds to rise. Except perhaps with bigger undercarriage wings.