Replying to Trampo springs question

k, so I got a 14ft jumpking tramp. its fun and all but ive reached the limit of stuff i can throw on it. cause a $200 tramp just doesnt give me the air i want. the springs for that trampoline are 8.5 inches and my question is could I use larger springs to give me more bounce? i know I would have to raise the tramp off the ground more to avoid bottoming out but would the mat stil work fine? or would there be too much slack in the mat causeing the springs to pop off or in anyway be unsafe or not work? thanks just trying to figure out a cheap way for more air and the tramp guys online will obviously say no.