Installation Time: Shop Install
Installation Cost: $250-$500
January 27, 2018
Very happy w/the FRPP 3.73's!!
I had OEM 3.73's on my former '08 Bullitt and loved them because they moved the powerband down low- lots better bottom end and quicker acceleration. My '14 GT Track Pack also came w/OEM 3.73's and loved them on that car for the same reason.
IMHO, the OEM 3.31's on my '09 GT500 made the bottom end feel soft. The 'experts' cautioned me against 3.73's, citing that the KR model of the GT500 had 3.73's because of the larger wheel size to which I said, 'bunk.' I was also warned about the MPG issue, which I chuckled at. The increase in bottom end and roll-on power was immediate and significant and my MPG has actually gone up.
The theory goes that your gas mileage will be grossly affected by 3.73's. Well, my Bullitt averaged 24-27 highway MPG, my '14 GT T/P was well over 22 highway MPG and I've actually noticed an INCREASE in highway MPG since the 3.73 gears were installed on the GT500. I'm guessing the engine is now sitting in the 'sweet spot,' especially during my daily commute, where the engine is running at near optimal performance. I've seen 25 MPG on some occasions but generally, the MPG has been up 2-3 MPG on the highway. I use to have to fill up every 2-3 days and now I'm getting at 4-5 days out of every tank.
3.73's are a win-win to me.
I will caution buyers to NOT buy used 3.73's. Sadly, that was a lesson I learned that cost me time and $$. The used gears looked perfect, brandy new even, yet once installed, they could not be properly aligned and the dreaded whine was ever-present. I'd never buy used gears again, don't care how pretty they look.
Spend the extra $$ and get new FRPP gears, as well as the proper type/amount of oil and ring/pinion installation kit. Lastly, and perhaps most importantly, make sure the shop you bring it to knows what it's doing. Nothing worse than listening to whining gears that were installed improperly.