Realistic expectations after installing revised exhaust
 

I have an 86' basically stock 3.3L turbo, and am going to the simple muffler off the 78-79 non-cat cars(for short-term test purposes only). The car runs 91 octane in So. Cal

I am guessing a 12-15hp bump, but is there any additional torque bump as well that anyone has seen or has been documented on these cars?

Thank you!
:D

At best you'll probably get a barely detectable improvement on throttle response- depending on how clogged your cat was. Couldn't tell you hp, but for a point of reference, I got a very noticeable increase in throttle response and 200 to 300 less rpm to reach full boost (1 bar) by replacing a similar setup you have with a rarlyl8 muffler only. Older style muffler can't be that good...

Unfortunately there is no difference in performance between the Euro muffler and the USA cat/muffler combo (assuming the cat is in good shape). My mufflers net 12-15WHP when compared to either of the OEM units. Not much I agree but the throttle response , sound, and loosing 30 pounds off the rear add to the improvement.