welcome to the wrx family. I use a backpack and a bungie net to strap it to my rear fender. the subframe works out great for the bungie hooks. As far as pipes I put a fmf powercore on mine and it seems to be working well. enjoy your wrx
I am very happy with the fmf powercore. I put the silent core inseret in mine. It took the noise level down alittle. Seemed to change the pitch of the sound more than anything. Bike has more of the same tone as my YZ250F and is quieter at an idel.
I have a 03 and 07 250f Both of them I shortened the pipe by 2 inches. It tucked the pipe up underneath the number plate. Both pipes are stock pipes. By doing this you gain horse power and reduce engine braking. I did my 03 and 07 at the same time. Rode the o3 first went out and instantly noticed the new power. Put it right back in the trailer and grabed the 07 same exact performace. With the wrx the powercore made about the same hp boost. I put the quiet core in it to bring it down a few db's. I want to go up 2 teeth on the rear sprocket now to make it a little mor yz like in the front end. Now since i ride the wrx all week when i get on my yzf i get caught off guard on the throttle the first few minutes I am on it.. takes time for the brain to adjust. Also on the yzf shorting the pipe made it pull out when your in a tall gear way more than with the pipe being stock. I ride a lot of really tight woods lots of elevation changes and areana cross tracks indoor.