I recently bought an 88 formula 305 and i noticed when i press the clutch to shift the rpm's drop and stay at 1200 or 1500 even when i come to a stop.. Where should i start? And also i found a cheap exhaust from jegs.. Anyone know if this is worth buying? Or a hunk of junk?

http://www.jegs.com/i/JEGS-Performan...oductId=872439

Also what will my engine benifit the most from modwise and will it be noticable

Sorry my spelling isnt perfect