I have been debating going to a bigger down pipe. Kinda expensive if you wont see much in return. I have been 137mph so far. Wonder what a bigger down pipe would do?
Consider going with 160's they should give you plenty of room. I hear they run fine especially on e85 as more fuel is needed. I most likely will be stepping up to them this season.
I recently put the QA1 R coil overs on the front of mine and so far so good. On a soft setting my car goes down the road much smoother. Only been to the track once with them and no issues as of yet.