I had t6's with minor mods and they sucked. Not only did they not fit right but the more mods you do the more the pipes make up changes. All i had done at the time was a cool head 20cc, advance timming, v-force reeds, K&N without lid and it ran like sh@@!#. Believe it or not stock banshees were hanging in for a while . Called Toomey and they even said they have had alot of trouble with the fit and they told me i should have read the description better it states they were designed to give a stock bike 20 hps on top end and 8-10 on low to mid range.Toomey stated that if a person was even going to advance the timing or change the filter these statistics would change.Thay said these pipes are great if the pipes were the only thing a person was going to do. They change mine out for t5's and i tell you what it made a world of difference. There was a noticeable difference and i love them.. So to save you time and money if you plan on doing any thing else to your bike stay away from the tr6's. In my opinion i love the t5's but i have also road with sst's, fatty's, paul turner mids, rockets, and many others because in our group of about 30 people everyone has something a little different. Hope this helps you a little but the most important thing to do is research the different pipes and buy the one that best fits your riding style.