Curious if I would get much power gain from putting a He351Cw on with my 75s? 

Are you currently running smokey or hot?

 

I was running clean with 100s and a wh1c, then I put a super b on, gained some midrange, lost some low end. Wasn’t a big improvement for cost and hassle of install. 

HE351 is the same as my hybrid expect it tiny exhaust housing.

 

HE351 (60/60/9)

HX35/40 Hybrid (60/60/12)

 

Personally, I would go for the hybrid before the HE351. Better exhaust flow.

you wont gain any power without more fuel.  The stock turbo is still flowing enough air for the stock turbo to be within it's map.   I would refer to the threads covering this in the past.

You would better off setting you goals on a good tuner first. HX35 can work with +100HP injectors with a good tuner.