The 3-bolt 70-series turbocharger for the 3.8-liter Buick--track-proven to run easy 10.50s--has enjoyed lasting popularity with Turbo Regal racers. A couple of years ago, 10.50 was good enough to win a lot of races, including the GSCA's red-hot Turbo Street Modified class--created for Buick racers who fit between the GSCA's Turbo Street Stock and the Turbo Street Eliminator groups.
But if there's one trend with the aging Turbo Buicks its that technology just keeps coming, and these days in TSM, you'd better be running 10.20s to high 9s if you want a chance in Hell of seeing the winner's circle. TSM is wildly popular due to its rule structure, which requires racers to utilize stock components like the block and crank and limits the maximum turbocharger size to a 70mm compressor wheel. While it is true that ultimately, the tune is the most important aspect of a TR's setup, occasionally a new component comes along that raises the bar--enter the Garrett GT turbocharger.