Just so you know if you dont have a cat the exhaust shops are a pain in the rear. Other than that there is no issue. My 86 has only glasspacks and true dual, no cats or o2 sensors even, they were broken out lol. No issues at all.

 

So do you think I'm better off getting a high flow cat or hollowing this one out and getting some flowmasters?

 

Brock not tryin to sound like an **** but your car doesn't really come into play here your has a edelbrock carb and a vac advance dist if i am not mystaken right? mean it is no longer computer contolled like his

if your heart set to run a cat get a highflow, if not and you get guff about no cats tell them the motor was swaped in from a 60's car! = no cats then lol

 

Alright I've been thinking about this for a little bit and have compiled a few questions options, please bare with me..


1) I hollow out the cat, and keep the oem mufflers pipes, which I'm no fan of.

2) What size is the downpipe? I know the stock 87 ss is 2.25" but where? (at down pipe before cat, after cat, after mufflers? idk lol) I know the manifolds go down together into one pipe but what size is it? because if i were to buy a cat back system (including a high flow cat), what input size would i need? my output size i plan to run 2.5's because if i ever swap in a 350 I'll be all set. as for mufflers, I want to run flowmaster 40s or super 40's I'm not sure, can anyone recommend some nice deep ones that sound like 40's but maybe a wee bit cheaper ? haha.

3) i do a straight pipe to two flowmaster mufflers, also not a fan because of inspections.


the exhaust on the car now is a OEM replacement but is brand new so i want to maybe try to sell the cat and the pipes and such and pay for my new aftermarket exhaust with it. What do you think?

 

Thats true, I always forget that they were computer controlled on those years. I dont know why.

 

alright so as of now i decided I'm going to keep the stock cat since its in good working condition, as for the exhaust, will 2.25" be sufficient for the 305 with flowmasters? I'm debating if i should get the 40's super 40's, or super 44 mufflers (pair). what do you guys think?

 

I think I decided I'm going to keep the stock cat since it is in working condition as of now. Once it starts to put I'm going to get a highflow and work my way towards the headers. My pipes are in GOOD condition so I'd like to maybe buy JUST the mufflers. Will flowmasters sound good with just 2.25 inch pipes? I'm debating on either the super 40 or super 44. which do you think sounds better and as far as intereior noise which is quieter? thanks alot. I didnt realize my phone posted my response because it refreshed, id like to delete it and post this one. Thanks again.

 

It was part of GM's "Computer Command Control" system. They put in the cat (Govt. Mandate since 1975), along with an O2 sensor (ahead of the cat and not heated) to improve emissions. They also had either a 2 or 4-barrel Rochester carb. with a throttle sensor, electronic spark control, electric choke (some models), mixture control (to improve MPG), other sensors in the air cleaner, smog pump, and about 10 miles of vacuum hoses. They were trying to squeeze as much MPG as they could before fuel injection took over in the '90s. The problem with all this is that HP output from V8s of that era was pathetic. The 307 V8 in my 82 Olds put out less HP then my 3.4 V6 does now. It only put out ~140hp as opposed to 180hp with the 3.4.

Hence that's why you have cars of that era with the cat removed, complete engine swaps, and a piece of electrical tape over the "Check Engine" light.

 

Any suggestions on the exhaust? Or Reccomendations for mufflers?

 

Thrush Welded for mufflers. Just like Blowmasters but half the price. Yes 2.25 will sound good and be plenty big for your 305.