That is to say I would like to understand how leadpipes are chosen for an instrument? Their must be some mathmatical formula that would haelp one get close to the ideal taper,begining and ending bore etc.....I have searched and no such luck. Their seems to be a lot of opinions on which leadpipes sound best but nothing objective to quantify the opinions. Recently I decided to look into some leadpipes for some trumpets I own. One of them has factory OEM parts still available but the other two do not. Now I can play the OEM guesing game and try different leadpipes from one of the OEM's hopeing that something they make today will fit and sound right. The other one is a complete no-go since the company is no longer in business. Now here is where a lot ofmy questions come in!!! Some places that repair brass instruments tell me "no problem they make leadpipes and are sure one of their exhisting leadpipes can be made to fit!" Well that is great but how do they know it will sound decent? Then some places tell me "Just get a Universal one from Allied Supply trim to fit and will fit most trumpets!" again how is this possable when so many people make a huge stink about the leadpipe needing to match the bell for good sound quality???? Then one company wants to send me "6" different leadpipes to play test on my trumpet. After selecting the best one I would then send back the other 5 haveing already paid the price for one leadpipe. So how can anyone use a universal and be good to go? How does an OEM chose one leadpipe out of so many possabilities since the leadpipe will respond differently to each person? What part does the reciever play in this mess??? It would seem to me that the space between the mouth piece and the leadpipe and the space between the leadpipe and the tuneing slide would play a huge role in all of this as well? How do those trumpets with interchangeable leappipes or bells make a tight seal? The ones I have seen online do not appear to use o-rings or anyting like that? What about material I understand how critical material can be for the bell but for the leadpipe I would imagine that instead of a material's resnate charteristics that corresion resistance would be a biger issue? Thanks guys and gals... I am really trying to understand this because it almost sounds like voodoo when you listen to some people talk about but their must be some science behind it?!?!?