Ha you must have my old setup then, me and Dan @ sjm made the first one.
Though a lot of people slated it, saying it wasn't as quick as it should have been and also that throttle response wasn't great etc BUT:
it made 193 bhp on RS tunings rollers, and over 200 bhp on 2 other rollers.
It ran the 1/4 mile at pod in 14.2 with full interior and 1/2 tank of fuel.
It had 145000 miles on and still had the cat in
And the biggest point - as we were the first, it was a mule - half of it was a complete guess - for example was the MAP tank - I made it far too big, it needed one at least half as big - the throttle response would have been much better.
We did it more to show it could be done, it cost me under £700 including all costs, so as it went well I was happy to have it that way - tbh I wish I had kept it and tweaked it a bit more.
But yes, if you want a package out the box then stand alone will be better, but for the money it cost me, I was happy