I just installed Flowmaster 50's on my '70 with 454/auto. The sound is much better but not obnoxious to anyone including the neighbors. Unfortunately I went with the 2.5" inlet & outlet which now causes me to look for another set of rectangular tips fo 70's. I think I may have caused myself a real problem as no one makes those tips for 2.5". I enjoy the sound and would go with the Flowmaster 50's not the 40's as they are too loud.

I have the Monza type with the chrome tips, red inside I got from Mid America and the sound is just right for me. Just the right amount of noise, awesome at idle and barkie if ya jump on them. Normal running they are fine for my ears. They were $129 bucks and connect from the Y pipe out.......Even wife likes them. slight rumble on the down hills, again, I like the sound. Did I mention I was 60 and hard of hearing....yupe I am in the high frequencys, but fine in the muffler range. I think they are just right if you like the 60's sounds, I do......Lot of people come over when its just sitting idling and comment on the sweet sound. Works for me......Good luck in your choice. I'm content with them just straight out of the Y pipe also and would probally like the chambered pipes also.... Mind is a 79 so waiting till I don't have to go thru inspection anymore before I go radical with it......

monzas or flowmasters, can't go wrong with either