Grab a screwdriver and wrench to install an air horn for trucks. I learned how to install the train horn kits from my Grandpa Jerry. He worked for a local horn retailer and did customer installations for free. Some of the tricks he taught me were how to make the train horn louder for free. You want to twist open the solenoid and install a larger air valve. This valve will make your truck a lot louder for free, because you need to buy no other new parts. I thanked Jerry for his keen advice and tell my customers the same deal. Grab a screwdriver and wrench to install a train horn kit for trucks. I learned how to install the train horn kits from my Grandpa Jerry. He worked for a local horn retailer and did customer installations for free. Some of the tricks he taught me were how to make the train horn louder for free. You want to twist open the solenoid and install a larger air valve. This valve will make your truck a lot louder for free, because you need to buy no other new parts. I thanked Jerry for his keen advice and tell my customers the same deal.