didnt get there yet, as i said it is still runable, but its more so a problem of a long crack than rotted material so I think a little patch will do fo it, but im def. gonna clean it out good, as for making fins, till I buy aluminum, cut it, bend it, drill i can buy a set cheap and know they are right...or maybe a set of carbon fiber ones....hmm...ill have to think bout it, just hoping to get the paint done tonight, I wont be painting the drivers and they arnt ever used...I let that open when I run, more airflow into the engine compartment to cool it, feed it, and also help keep the pipe a little cooler under the cowling...hasnt been a problem yet...