TPI's are great. They are reliable, inexpensive, and produce great useable torque that make a vehicle fitted with one very enjoyable to drive
Personally I've made it a mission to see how far I can take one. There is still a lot of hobbiest support for the platform. I've managed to fit mine with crank triggered distributorless ignition all while using the GM 1227730 ECM. The ECM also controls my 2 electric fans, AC compressor, exhaust dump valve, TCC in a very RPM and load precise way.
It's been dyno proven that a bone stock TPI on top of good heads can flow enough for 400HP and much more if modified. There are many ways to modify the platform most high HP setups are using different manifolds.
Soon they may be in vogue again because they are attractive to look at and technology has been out of production for almost 30 years. I love the LS platform, but they just dont look right in classic street rod.
My 406 with a near stock 210/219 cam idles dead smooth and ran an easy 12.9 at 110 mph the first time I tired with wheel spin all through 1st gear. I think it can be a high 11 second car with some tweaking and a good launch.