I think he is wanting to paint it Lemon Twist, but wants to make sure it has pop. The color itself is one of the hardest to get right. When I mean right, I mean close to the original without looking to bright or pale. Kinda like FC7 Plum Crazy. FC7 and FY1 are really hard to spray right. The secret is all with how it's painted. I can take the same factory PPG Lemon Twist mix and paint it so it looks bright or change the way I spray and it looks pale. It's all in how it's application technique, what it's applied over and how many coats. If you read the spec sheet for PPG Lemon Twist (to get the correct shade) it calls for it to be placed over a white sealer base and to use 2 to 3 coats. I've found that 2 coats over white sealer leaves the color a little on the bright side and 3 coats is too pale and 4 coats is all wrong. But only using 2 coats runs the risk of seeing stripes and doesn't have enough coverage. This is using a 1.3 tip Sata RP which puts down a lot of paint for high end paint jobs. For example, if using a Iwata Supernova gun it would lay down a little less paint and 3 coats might be closer to right. The gun, speed, air pressure, and distance it's sprayed all play a HUGE factor in how it will look (the tone and shade). I had to slightly adjust the mix to get that 2.5 coat correct look after 4 coats.
So what I'm telling you is have your painter do some VERY specific spray outs over the exact sealer color you will be using. Send me your phone number and I can talk you through it. Or I can talk to your painted and give him some tips on how to get the right color. I'll even share with him my custom mix that makes it a dead on match at 4 coats.