There will always be a gain TBH. The castings are always crap!
There are a couple of people offering this modification...on the scheme of things, its not hard, its not like re-working a head port for example...so its hard to get "wrong". Saying that workmanship often varies, and thats what makes the difference between a nice job, and something that looks home-done.
I dont just match the ones I do either. Its good practice to sort the casting flash on the runner sides, and there are a couple of smaller areas which can be worked to again, make it a better job.
There are a couple of people offering this modification...on the scheme of things, its not hard, its not like re-working a head port for example...so its hard to get "wrong". Saying that workmanship often varies, and thats what makes the difference between a nice job, and something that looks home-done.
I dont just match the ones I do either. Its good practice to sort the casting flash on the runner sides, and there are a couple of smaller areas which can be worked to again, make it a better job.